All GMAT Math Resources
Example Questions
Example Question #1 : Dsq: Calculating The Length Of The Hypotenuse Of An Acute / Obtuse Triangle
Find the hypotenuse of an obtuse triangle.
Statement 1: Two given lengths with an inscribed angle.
Statement 2: Two known angles.
Statement 1: Two given lengths with an inscribed angle.
Draw a picture of the scenario. The values of , , and angle are known values.
Use the Law of Cosines to determine side length .
Statement 2: Two known angles.
There is insufficient information to solve for the length of the hypotenuse with only two interior angles. The third angle can be determined by subtracting the 2 angles from 180 degrees.
The triangle can be enlarged or shrunk to any degree with any scale factor and still yield the same interior angles. There must also be at least 1 side length in order to calculate the hypotenuse of the triangle by the Law of Cosines.
Therefore:
Example Question #1 : Dsq: Calculating The Length Of The Hypotenuse Of An Acute / Obtuse Triangle
Find the length of the hypotenuse of obtuse triangle TLC:
I)
II) Side T is
Either statement is sufficient to answer the question.
Neither statement is sufficient to answer the question. More information is needed.
Both statements are needed to answer the question.
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.
Find the length of the hypotenuse of obtuse triangle TLC:
I)
II) Side T is
Using I), we can find the measure of all 3 angles:
Next, use II) and the Law of sines to find the hypotenuse:
And we needed both statements to find it!
Example Question #1 : Dsq: Calculating The Length Of The Hypotenuse Of An Acute / Obtuse Triangle
For obtuse triangle ABC, what is the length of c?
(1) and
(2) c is an integer,
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
EACH statement ALONE is sufficient.
BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient.
Since this is an obtuse triangle, pythagorean theorem does not apply.
Statement 1 by itself will only determine a range of values c utilizing the 3rd side rule of triangles. . Therefore, statement 1 alone is insufficient.
Statement 2 by itself will determine that c is either 10 or 11. Therefore, statement 2 alone is insufficient.
When taken together, statements 1 and 2 define a definitive value for c: . Therefore, BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient.
Example Question #2 : Dsq: Calculating The Length Of The Hypotenuse Of An Acute / Obtuse Triangle
. What is the measure of c?
(1)
(2)
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
Since , , , therefore, thus making this an acute triangle. Pythagorean theorem will not apply.
With the information in statement 1, we can't determine the lengths of any other sides. Therefore, Statement 1 alone is not sufficient.
With the information in statement 2, we can't determine the lengths of any other sides. Therefore, Statement 2 alone is not sufficient.
Using the Third Side Rule for triangles, the information in statements 1 and 2 together would allow us to determine the range of values for c. , but this does not provide a definitive value for c. Therefore, Both statements together are not sufficient.
Therefore - the correct answer is Statements (1) and (2) TOGETHER are NOT sufficient.
Example Question #41 : Triangles
Note: Figure NOT drawn to scale.
What is the area of the above arrow?
Statement 1:
Statement 2:
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.
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.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT 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.
It can already be ascertained from the figure that , since the left portion is a rectangle, so Statement 2 is redundant.
We can already calculate the area of the rectangular portion of the arrow:
All this is left is to calculate the area of the triangular portion. If we know Statement 1, we can take half the product of the height, which is 13, and the base, which is :
Add these numbers to get the area of the arrow:
Example Question #2 : Dsq: Calculating The Area Of An Acute / Obtuse Triangle
Two of the vertices of a triangle on the coordinate plane are . What is its area?
Statement 1: The -coordinate of the third vertex is 8.
Statement 2: The -coordinate of the third vertex is 5.
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.
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 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.
The triangle has as its base a vertical line of length 7, so the height of the triangle would be the perpendicular - which in this case is horizontal - distance from that base. Since the base is part of the -axis, this distance is the absolute value of the -coordinate, which is ony given by Statement 1. Statement 2 is irrelevant.
This is illustrated by this diagram:
Example Question #42 : Triangles
What is the area of a triangle on the coordinate plane with two of its vertices at ?
Statement 1: The -coordinate of its third vertex is 6.
Statement 2: The -coordinate of its third vertex is 8.
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.
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.
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.
The area of a triangle is half the product of its base and its height.
The triangle has as its base a horizontal line of length 10, so the height of the triangle would be the perpendicular - which in this case is vertical - distance from the third vertex to that base. Since the base is part of the -axis, this height is the absolute value of the -coordinate, which is only given by Statement 2. Statement 1 turns out to be irrelevant.
This is illustrated by this diagram:
Example Question #1 : Dsq: Calculating The Length Of The Side Of An Acute / Obtuse Triangle
Is the triangle isosceles?
Statement 1: The triangle has vertices A(1,5), B(4,2), and C(5,6).
Statement 2:
Statement 1 ALONE is sufficient, but statement 2 is not sufficient.
EACH statement ALONE is sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
Statement 2 ALONE is sufficient, but statement 1 is not sufficient.
Statements 1 and 2 TOGETHER are NOT sufficient.
EACH statement ALONE is sufficient.
For a triangle to be isosceles, two of the sides must be equal. To determine wheter this is true, we must have the three side lengths. Statement 2 gives us those three side lengths. However, Statement 1 also gives us all of the information we need by giving us the three vertices. By using the distance formula, we can easily get the three triangle sides from the vertices. Therefore both statements alone are sufficient.
Example Question #2 : Dsq: Calculating The Length Of The Side Of An Acute / Obtuse Triangle
Note: Figure NOT drawn to scale.
The above shows a triangle inscribed inside a rectangle . is isosceles?
Statement 1: is the midpoint of .
Statement 2:
Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT 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.
BOTH statements TOGETHER are insufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.
EITHER statement ALONE is sufficient to answer the question.
We show Statement 1 alone is sufficient:
If is the midpoint of , then . Opposite sides of a rectangle are congruent, so ; all angles of a rectangle, being right angles, are congruent, so . This sets up the conditions for the Side-Angle-Side Theorem, and . Consequently, , and is isosceles.
Now, we show Statement 2 alone is sufficient:
If , and are congruent, then and , being complements of congruent angles, are congruent themselves. By the Isosceles Triangle Theorem, is isosceles.
Example Question #3 : Dsq: Calculating The Length Of The Side Of An Acute / Obtuse Triangle
Which side of is the longest?
Statement 1: is an obtuse angle.
Statement 2: and are both acute angles.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT 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.
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.
If we only know that two interior angles of a triangle are acute, we cannot deduce the measure of the third, or even if it is obtuse or right; therefore, Statement 2 alone does not help us.
If we know that is an obtuse angle, however, we can deduce that and are both acute angles, since at least two interior angles of a triangle are acute. Therefore, we can deduce that has the greatest measure, and that its opposite side, , is the longest.