GMAT Math : Geometry

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #1 : Dsq: Calculating The Angle Of An Intersection

Lines

Note: Figure NOT drawn to scale.

Refer to the above diagram. Evaluate .

Statement 1: 

Statement 2: 

Possible Answers:

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.

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.

BOTH statements TOGETHER are insufficient to answer the question. 

Correct answer:

BOTH statements TOGETHER are insufficient to answer the question. 

Explanation:

We show that both statements together give insufficient information. Assume both statements together. Consider the following two cases:

Case 1: 

Since the angles of measures  and  form linear pairs with the angle of measure , each is supplementary to that angle and, subsequently,  .

The angle of measure  is vertical to the angle of measure , so the two must be congruent; .

From Statement 1, 

Since  and , then .

These values are therefore consistent with the diagram and with both statements.

 

Case 2: 

We can find the values of the other variables as before:

, so .

Again, all values are consistent with the diagram and both statements. 

 

Since at least two different values of  satify the conditions, the two statements are insufficient.

 

Example Question #6 : Dsq: Calculating The Angle Of An Intersection

Transversal

Note: Figure NOT drawn to scale. Do not assume lines are parallel or perpendicular simply by appearance.

Evaluate .

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.

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 insufficient 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:

Statement 1 alone gives us that , but reveals no clues about any of the eight angle measures. From Statement 2 alone, that , we can assume that , and  all have measure , but no clues are given about any of the other four angles—in particular, .

Assume both statements are true. From Statement 1, , and by way of the Parallel Postulate, corresponding angles have the same measure—in particular, . From Statement 2, we know that . From these two statements, .

Example Question #5 : Dsq: Calculating The Angle Of An Intersection

Chord

Note: Figure NOT drawn to scale.

Give the measure of  in the above diagram.

Statement 1:  is an arc of measure .

Statement 2:  is an arc of measure .

Possible Answers:

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.

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.

BOTH statements TOGETHER are insufficient 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:

If two chords of a circle intersect inside it, then the measure of an angle formed is equal to the arithmetic mean of the measures of arc it intercepts and the arc its vertical angle intercepts. In other words, in this diagram,

Both arc measures are needed to find the measure of the angle. Neither statement alone give both; the two together do.

Example Question #1 : Squares

Find the length of the diagonal of square G.

I) The area of G is  fathoms squared.

II) The side length of G is  fathoms.

Possible Answers:

Each statement alone is enough to solve the question.

Both statements taken together are sufficient to solve the problem.

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

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.

Correct answer:

Each statement alone is enough to solve the question.

Explanation:

We can use the side length and the Pythagorean Theorem to find the diagonal of a square.

We can find side length from area, so we could solve this with either I or II.

Example Question #1 : Squares

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The circle with center  is inscribed in square . What is the length of diagonal ?

(1) The area of the circle is .

(2) The side of the square is .

Possible Answers:

Statement 1 alone is sufficient.

Statements 1 and 2 together are not sufficient.

Both statements together are sufficient.

Statement 2 alone is sufficient.

Each statement alone is sufficient.

Correct answer:

Each statement alone is sufficient.

Explanation:

The diagonal of the square can be calculated as long as we have any information about the lengths or area of the circle or of the square.

Statement 1, by giving us the area of the circle, allows us to find the radius of the circle, which is half the length of the side. Therefore statement 1 alone is sufficient.

Statement 2, by telling us the length of a side of the square is also sufficient, and would allow us to calculate the length of the diagonal.

Therefore, each statement alone is sufficient.

Example Question #2 : Squares

On your college campus there is a square grassy area where people like to hangout and enjoy the sun. While walking with some friends, you decide to take the shortest distance to the corner of the square opposite from where you are. Find the distance you traveled.

I) The perimeter of the square is  meters.

II) The square covers an area of  square meters.

Possible Answers:

Either statement is sufficient to answer the question.

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

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.

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

Correct answer:

Either statement is sufficient to answer the question.

Explanation:

We are asked to find the length of a diagonal of a square.

We can do this if we have the side length. We can find side length from either perimeter or area.

 

From Statement I)

In this case, our side length is 15 meters.

We can use this and Pythagorean Theorem or 45/45/90 triangles to find our diagonal.

From Statement II)

From here, we can plug the side length into the Pythagorean Theorem like before and solve for the diagonal.

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

 

Example Question #4 : Quadrilaterals

Find the length of the diagonal of square A if the diagonal of square B is .

  1. The perimeter of square B is 
  2. The area of square A 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.

Statements 1 and 2 are not sufficient, and additional data is needed 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.

Correct answer:

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

Explanation:

Statement 1: The information provided would only be useful if the ratio of square A to square B was known. 

Statement 2: We need the length of the square's side to find the length of the diagonal and we can use the area to solve for the length of the side. 

Now we can find the diagonal: 

Example Question #5 : Dsq: Calculating The Length Of The Diagonal Of A Square

What is the length of the diagonal of the square?

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

Each statement alone is sufficient to answer the question.

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

Statements 1 and 2 are not sufficient, and additional data is needed 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.

Correct answer:

Each statement alone is sufficient to answer the question.

Explanation:

The length of the diagonal of a square is given by , where  represents the square's side. As such, we need the length of the square's side.

Statement 1: 

Statement 2: 

Both statements provide us with the length of the square's side. 

Example Question #5 : Quadrilaterals

The diagonal bracing of a square pallet measures . What is the area of the pallet?

Possible Answers:

Correct answer:

Explanation:

Squarecut To solve this problem, we must recognize that the diagonal bisector creates identical 45˚ - 45˚ - 90˚ right triangles. This means that, if the sides of the square are  then the diagonal must be . We can then set up the following equation:

If  then the area must be:

Example Question #1 : Quadrilaterals

Is Rectangle  a square?

Statement 1: 

Statement 2: 

Possible Answers:

EITHER 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.

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.

Correct answer:

EITHER statement ALONE is sufficient to answer the question.

Explanation:

A rectangle, by definition, is a parallelogram. Statement 1 asserts that the diagonals of this parallelogram are perpendicular. Statement 2 asserts that adjacent sides of the parallelogram are congruent, so, since opposite sides are also congruent, this makes all four sides congruent. From either statement alone, it can be deduced that Rectangle  is a rhombus. A figure that is a rectangle and a rhombus is by definition a square.

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