GMAT Math : Geometry

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #6 : Dsq: Calculating The Area Of A Square

True or false: 

Statement 1: A square with sidelength  has perimeter greater than 100.

Statement 2: A square with sidelength  has area greater than 40.

Possible Answers:

EITHER STATEMENT ALONE provides sufficient information to answer the question.

BOTH STATEMENTS TOGETHER provide sufficient information to answer the question, but NEITHER STATEMENT ALONE provides sufficient information to answer the question.

STATEMENT 2 ALONE provides sufficient information to answer the question, but STATEMENT 1 ALONE does NOT provide sufficient information to answer the question.

STATEMENT 1 ALONE provides sufficient information to answer the question, but STATEMENT 2 ALONE does NOT provide sufficient information to answer the question.

BOTH STATEMENTS TOGETHER do NOT provide sufficient information to answer the question.

Correct answer:

STATEMENT 1 ALONE provides sufficient information to answer the question, but STATEMENT 2 ALONE does NOT provide sufficient information to answer the question.

Explanation:

Assume Statement 1 alone. The perimeter of a square is four times the length of a side, which here is ; the perimeter is greater than 100, so

Therefore, the question can be answered in the affirmative from Statement 1 alone. 

Statement 2 alone gives insufficient information, however. The area of a square is the square of the length of a side. If the sidelength is , for example, the area is the square of this, which is 81; if the sidelength is , the area is 121. Both areas exceed 40, but only in the second case is .

Example Question #1 : Dsq: Calculating The Perimeter Of A Square

Gene is building a fence. He is using square fence posts and needs to know the total distance around one pole. Help him find the distance,

I) The fence will be  feet tall and  feet long.

II) The diagonal distance from one corner of a fence post to its other corner is   inches.

 

Possible Answers:

Statement II is sufficient to answer the question, but statement I is not sufficient to answer the question. 

Statement I is sufficient to answer the question, but statement II is not sufficient to answer the question.

Both statements are needed to answer the question.

Either statement is sufficient to answer the question.

Neither statement is sufficient to answer the question. More information is needed.  

Correct answer:

Statement II is sufficient to answer the question, but statement I is not sufficient to answer the question. 

Explanation:

We are asked to find the perimeter of a square. To do that we need a side length.

I) Is irrelevant and is trying to distract you with other aspects of the question.

II) Gives you the diagonal of the square. The diagonal of a square creates two 45/45/90 triangles.

Use this knowledge to find the other side lengths and then the perimeter.

 

 

 

Example Question #2 : Dsq: Calculating The Perimeter Of A Square

Find the perimeter of the square.

  1. The length of the diagonal of the square is .
  2. The area of the square is .
Possible Answers:

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.

Each statement alone is sufficient to answer the question.

Both statements taken together are sufficient to answer the question, but neither statement alone is sufficient.

Statements 1 and 2 are not sufficient, and additional data is needed to answer the question.

Correct answer:

Each statement alone is sufficient to answer the question.

Explanation:

Statement 1: The length of the diagonal of a square is found by multiplying the length of one side by the square root of . In this case, it is easy to see the length of the side is .

Knowing the length of the side, we can find the perimeter of the square:

 

Statement 2: We can use the given area to solve for the length of the side

where  represents the side's length

We can now find the perimeter in the same manner: 

       

Therefore, each statement alone is sufficient to answer the question.

 

Example Question #61 : Geometry

The ratio of square A to square B is 3:1. Find the perimeter of square B

  1. The area of square is .
  2. The length of the diagonal of square B is .
Possible Answers:

Statements 1 and 2 are not sufficient, and additional data is needed to answer the question.

Statement 2 alone is sufficient, but statement 1 alone is not sufficient to answer the question.

Both statements taken together are sufficient to answer the question, but neither statement alone is sufficient.

Statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question.

Each statement alone is sufficient to answer the question.

Correct answer:

Each statement alone is sufficient to answer the question.

Explanation:

Statement 1: We can use the area to find the length of square A's side.

  Keep in mind that the ratio of square A to square is 3:1.

   Now that we know the length of the side, we can find the perimeter of square B.

 

Statement 2: We can use the diagonal to find the length of the side.

We can easily see the side measures  so we can now find the perimeter.

Example Question #62 : Geometry

What is the perimeter of the square? 

  1. A side measures .
  2. The area of the square is .
Possible Answers:

Both statements taken together are sufficient to answer the question, but neither statement alone is sufficient.

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.

Statement 2 alone is sufficient, but statement 1 alone is not sufficient to answer the question.

Each statement alone is sufficient to answer the question.

Correct answer:

Each statement alone is sufficient to answer the question.

Explanation:

Recall the formula for perimeter of a square:

 

where  represents the length of a side. 

Statement 1: We're given  so we can find the perimeter: 

Statement 2: We're given the area  so we can solve for .

With , we can calculate the perimeter: 

 

Each statement alone is sufficient to answer the question.

Example Question #5 : Dsq: Calculating The Perimeter Of A Square

Find the perimeter of the square.

  1. The diagonal measures  inches.
  2. The diagonal is found by  where  represents a square's side length.
Possible Answers:

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.

 

Statement 2 alone is sufficient, but statement 1 alone is not sufficient to answer the question.

Correct answer:

Statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question.

 

Explanation:

Statement 1: We can find the length of the square's side using the information given. 

 

so 

We can now find the perimeter of the square:  inches

Statement 2: In order to find the length of the square's side using the information provided in Statement 1, we need to use this equation. 

Statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question.

 

Example Question #1 : Other Quadrilaterals

Parallelogram

NOTE: Figure NOT drawn to scale.

Is the above figure a parallelogram?

Statement 1: 

Statement 2: 

Possible Answers:

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.

BOTH statements TOGETHER are insufficient 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.

Correct answer:

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Explanation:

Knowing one pair of sides of a quadrilateral to be congruent is not alone sufficient to prove that figure to be a parallelogram, nor is knowing one pair of sides of a quadrilateral to be parallel. But knowing both about the same pair of sides is sufficient by a theorem of parallelograms.

Example Question #61 : Geometry

Trapezoid

Notes:  refers to the length of the entire dashed line. Figure not drawn to scale.

 

Calculate , the height of the large trapezoid.

Statement 1: 

Statement 2: The area of the trapezoid is 7,000.

Possible Answers:

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 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.

Correct answer:

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Explanation:

Consider the area formula for a trapezoid:

 is the midsegment of the trapezoid, which, by the Trapezoid Midsegment Theorem, has length equal to the mean of the bases - in other words, . The area formula can be expressed, after substitution, as 

So, if you know both the area and  - but not just one - you can find the height by dividing.

Example Question #62 : Geometry

Consider parallelogram .

I) The perimeter of  is  light years.

II) Side  is  light years and is equivalent to side .

Find the length of side .

Possible Answers:

Statement II is sufficient to answer the question, but statement I is not sufficient to answer the question.

Either statement is sufficient to answer the question.

Statement I is sufficient to answer the question, but statement II is not 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.

Correct answer:

Both statements are needed to answer the question.

Explanation:

We can work backwards from the perimeter to find the length of the unknown side.

I) Gives us the perimeter.

II) Gives us two of the sides.

In a parallelogram there are two sets of corresponding sides. We can use I) and II) to write the following equaiton, where l is the length of our wanted side.

Solve for l to find our final side:

Example Question #1 : Dsq: Calculating The Length Of The Side Of A Quadrilateral

Calculate the side of a square.

Statement 1:  A circle with an area of  is enclosed inside the square and touches all four edges of the square.

Statement 2:  A circle with a circumference of  encloses the square and touches all four corners of the square.

Possible Answers:

Correct answer:

Explanation:

Statement 1:  A circle with an area of  is enclosed inside the square and touches all four edges of the square.

Write the formula for the area of the circle.

 

After substituting the value of the area and solve for radius, the radius is 1.  The side length of the square is double the length of the radius.

Statement 2:  A circle with a circumference of  encloses the square and touches all four corners of the square.

Write the formula for the circumference of the circle.

After substituting the value of the circumference and solve for diameter, the diameter of the circle is 1.  This diameter represents the diagonal of the square.  Because the square length and width are equal dimensions, it is possible to solve for the lengths of the square by Pythagorean Theorem knowing just the length of the square diagonal.

Therefore:

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