All GMAT Math Resources
Example Questions
Example Question #12 : Dsq: Calculating The Area Of An Equilateral Triangle
Give the area of equilateral triangle .
Statement 1: is a diameter of a circle with circumference .
Statement 2: is a side of a 45-45-90 triangle with area .
BOTH statements TOGETHER are insufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Assume Statement 1 alone. To find the diameter of a circle with circumference , divide the circumference by to get . This is also the length of each side of the triangle, so we can get the area using the area formula:
.
Assume Statement 2 alone. A 45-45-90 Triangle has congruent legs, and the area is half the product of their lengths, so if we let be the common sidelength,
By the 45-45-90 Theorem, the hypotenuse has length times this, or .
Since it is not given whether is a leg or the hypotenuse of a right triangle, however, the length of - and consequently, the area - is not clear.
Example Question #2551 : Gmat Quantitative Reasoning
Find the area of an equilateral triangle.
- A side measures .
- An angle measures .
Statement 2 alone is sufficient, but statement 1 alone is not sufficient to answer the question.
Statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question.
Both statements taken together are sufficient to answer the question, but neither statement alone is sufficient.
Each statement alone is sufficient to answer the question.
Statements 1 and 2 are not sufficient, and additional data is needed to answer the question.
Statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question.
In an equilateral triangle all sides are of the same length and all internal angles measure to .
Statement 1:
Where represents the length of the side.
If we're given the side, we can calculate the area:
Statement 2: We don't need the angle to find the area.
Example Question #71 : Triangles
Consider equilateral triangle .
I) The area of triangle is .
II) Side is .
What is the height of ?
Neither statement is sufficient to solve the question. More information is needed.
Statement 1 is sufficient to solve the question, but statement 2 is not sufficient to solve the question.
Statement 2 is sufficient to solve the question, but statement 1 is not sufficient to solve the question.
Both statements taken together are sufficient to solve the question.
Each statement alone is enough to solve the question.
Each statement alone is enough to solve the question.
Since is states that we are working with a equilateral triangle we can use the formula for area:
where is the side length. Once we have calculated the side length we can then plug that value along with the area into the equation:
and solve for h.
Consider that equilateral triangles have equal sides. This means we can make ABC into two smaller triangles with hypotenuse of 13 and base of 6.5. We can use that to find the height. We can find the height using statement II.
Therefore, both statements alone are sufficient to solve the question.
Example Question #1 : Dsq: Calculating The Height Of An Equilateral Triangle
What is the length of the height of ?
(1) , is the midpoint of
(2)
Both statements together are sufficient
Statement 1 alone is sufficient
Statements 1 and 2 taken together are not sufficient
Statement 2 alone is sufficient
Each statement alone is sufficient
Both statements together are sufficient
Firslty, we would need to have the length of the other sides of the triangles to calculate the height. Information about the angles could also be able to see whether the triangle is a special triangle.
From statement one we can say that triangle ABC is an equilateral triangle, since D is the mid point of the the basis. Moreover knowing , we can see that angle is 60 degrees. Since D, the basis of the height is the midpoint it follows that is also 60 degrees. Therefore is also 60 degrees. Hence the triangle is equilateral. However, we don't know the length of any of the side.
Statement 2 gives us the piece of missing information. And alone statement 2 doesn't help us find the height.
It follows that both statements together are sufficient.
Example Question #3 : Dsq: Calculating The Height Of An Equilateral Triangle
The equilateral triangle is inscribed in the circle. What is the length of the height?
(1) The center of the circle is at of the vertices A, B and C.
(2) .
Statement 2 alone is sufficient.
Both statements together are sufficient.
Statements 1 and 2 taken together are not sufficient.
Each statement alone is sufficient.
Statement 1 alone is sufficient.
Statements 1 and 2 taken together are not sufficient.
To be able to answer the question, we would need information about the radius or about the sides of the triangle.
Statement 1 tells us that the center of the circle is at of the vertice. However this is a property and it will be the same in any equilateral triangle inscribed in a circle, indeed, the heights, whose intersection is the center of gravity, all intersect at of the vertices.
Statement 2 also tells us something that we could have known from the properties of equilateral triangles. Indeed, equilateral triangles have all their 3 angles equal to .
Even by taking both statements together, we can't tell anything about the lengths of the height. Therefore the statements are insufficient.
Example Question #4 : Dsq: Calculating The Height Of An Equilateral Triangle
Consider the equilateral .
I) Side .
II) has an area of .
What is the height of ?
Neither statement is sufficient to answer the question. More information is needed.
Statement I is sufficient to answer the question, but statement II is not sufficient to answer the question.
Statement II is sufficient to answer the question, but statement I is not sufficient to answer the question.
Both statements are needed to answer the question.
Either statement is sufficient to answer the question.
Either statement is sufficient to answer the question.
I) Gives us the length of side w. Since this is an equilateral triangle, we really are given all three sides. From here we can break WHY into two smaller triangles and use either Pythagorean Theorem (or 30/60/90 triangle ratios) to find the height.
II) Gives us the area of WHY. If we recognize the fact that we can make two smaller 30/60/90 triangles from WHY, then we can make an equation with one variable to find the height.
Solve the following for b:
Thus, either statement is sufficient to answer the question.
Example Question #5 : Dsq: Calculating The Height Of An Equilateral Triangle
is an equilateral triangle. An altitude of is constructed from to a point on .
What is the length of ?
Statement 1: has perimeter 36.
Statement 2: has area .
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
From either statement alone, it is possible to find the length of one side of ; from Statement 1 alone, the perimeter 36 can be divided by 3 to yield side length 12, and from Statement 2 alone, the area formula for an equilateral triangle can be applied as follows:
Once this is found, the length of altitude can be found by noting that this divides the triangle into two congruent 30-60-90 triangles and by applying the 30-60-90 Theorem:
and
Example Question #5 : Dsq: Calculating The Height Of An Equilateral Triangle
Given equilateral triangles and , construct the altitude from to on , and the altitude from to on .
Which, if either, is longer, or ?
Statement 1:
Statement 2:
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Assume Statement 1 alone. If altitude of is constructed, the right triangle is constructed as a consequence. is a leg and the hypotenuse of , so . Since by Statement 1, it is given that , then by substitution, , so is the longer altitude.
Assume Statement 2 alone.
, so
divides into two 30-60-90 triangles, one of which is with shorter leg and hypotenuse , so by the 30-60-90 Theorem,
Again, and is the longer altitude.
Example Question #7 : Dsq: Calculating The Height Of An Equilateral Triangle
is an equilateral triangle. An altitude of is constructed from to a point on .
True or false:
Statement 1: A circle of area less than can be inscribed inside .
Statement 2: is a chord of a circle of area .
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
BOTH statements TOGETHER are insufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
Assume Statement 1 alone. The inscribed circle, or "incircle," of a triangle has as its center the mutual point of intersection of the bisectors of the three angles, which, in the case of an equilateral triangle, coincide with the altitudes. , its three altitudes, and the incircle are shown below:
If the area of the incircle is less than , then the upper bound of the radius, which is , can be found as follows:
and has length less than 4. Also, the point of intersection of the three altitudes divides each altitude into two segments, the ratio of whose lengths is 2 to 1, so
and
Therefore, Statement 1 only tells us that , leaving open the possibility that may be less than, equal to or greater than 10.
Assume Statement 2 alone. The radius of a circle of area can be found as follows:
The diameter of the circle is twice this, or . Since the longest chords of a circle are its diameters, then any chord in this circle must have length less than or equal to this. Statement 2 tells us that
Now examine the above diagram. , as half of an equilateral triangle, is a 30-60-90 triangle, so by the 30-60-90 Triangle Theorem,
and
is therefore a true statement.
Example Question #1 : Dsq: Calculating The Height Of An Equilateral Triangle
is an equilateral triangle. An altitude of is constructed from to a point on .
What is the length of ?
Statement 1: is inscribed inside a circle of circumference .
Statement 2: is a chord of a circle of area .
BOTH statements TOGETHER are insufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
Assume Statement 1 alone. The circumscribed circle, or "circumcircle," of a triangle has as its center the mutual point of intersection of the perpendicular bisectors of the three sides, which, in the case of an equilateral triangle, coincide with the altitudes. , its three altitudes, and the circumcircle are shown below:
The circle has circumference , so its radius, which is equal to the length of , can be found by dividing this by to yield
.
Also, the point of intersection of the three altitudes divides each altitude into two segments, the ratio of whose lengths is 2 to 1, so
.
Assume Statement 2 alone. The radius of the circle can be found using the area formula for the circle, and the diameter can be found by doubling this. This diameter, however, only provides an upper bound for the length of a chord of the circle; if is a chord of this circle, its length cannot be determined, only a range in which its length must fall. Therefore, Statement 2 is insufficient.