ACT Math : Quadrilaterals

Study concepts, example questions & explanations for ACT Math

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Example Questions

Example Question #51 : Kites

A kite has a side length of  and another side length of . Find the perimeter of the kite.

Possible Answers:

Correct answer:

Explanation:

By definition a kite must have two sets of equivalent sides. Since we know that this kite has a side length of  and another side with a length of , each of these two sides must have one equivalent side.

The perimeter of this kite can be found by applying the formula:

 





Note, though, that  does not appear as an answer choice. Thus, convert  into  by:


Example Question #51 : Quadrilaterals

A kite has a side length of  and another side length of . Find the perimeter of the kite.

Possible Answers:

Correct answer:

Explanation:

 a kite must have two sets of equivalent sides. Since we know that this kite has a side length of  and another side with a length of , each of these two sides must have one equivalent side.

The perimeter of this kite can be found by applying the formula:

 





Note: the correct solution can also be found by: 

Example Question #52 : Quadrilaterals

A kite has a side length of  and another side length of . Find the perimeter of the kite.

Possible Answers:

Correct answer:

Explanation:

 A kite must have two sets of equivalent sides. Since we know that this kite has a side length of  and another side length of , each of these two sides must have one equivalent side.

The perimeter of this kite can be found by applying the formula:

 



Example Question #31 : Kites

Find the area of a kite with the diagonal lengths of  and .

Possible Answers:

Correct answer:

Explanation:

Write the formula to find the area of a kite.  Substitute the diagonals and solve.

Example Question #1 : How To Find The Area Of A Kite

Find the area of a kite with diagonal lengths of  and .

Possible Answers:

Correct answer:

Explanation:

Write the formula for the area of a kite.

Plug in the given diagonals.

Pull out a common factor of two in  and simplify.

Use the FOIL method to simplify.

Example Question #31 : Kites

Find the area of a kite if one diagonal is  long, and the other diagonal is  long.

Possible Answers:

 

Correct answer:

Explanation:

The formula for the area of a kite is 

Plug in the values for each of the diagonals and solve.

Example Question #51 : Quadrilaterals

If a trapezoid has a height of 14, base lengths of 10 and 12, and side lengths of 13, what is its perimeter?

Possible Answers:

Correct answer:

Explanation:

Use the formula for perimeter of a trapezoid:

Where  is the perimeter,  and  are the lengths of the bases, and  is the length of the side.

In this case:

Example Question #1 : How To Find An Angle In A Trapezoid

Find the measure of angle  in the isosceles trapezoid pictured below.

Screen_shot_2013-03-18_at_3.32.40_pm

 

Possible Answers:

Correct answer:

Explanation:

The sum of the angles in any quadrilateral is 360°, and the properties of an isosceles trapezoid dictate that the sets of angles adjoined by parallel lines (in this case, the bottom set and top set of angles) are equal. Subtracting 2(72°) from 360° gives the sum of the two top angles, and dividing the resulting 216° by 2 yields the measurement of x, which is 108°.

Example Question #2 : How To Find An Angle In A Trapezoid

Trapezoid  is an isosceles trapezoid with angle . If  and   are paired, what is the measure of ?

Possible Answers:

Correct answer:

Explanation:

As a rule, adjacent (non-paired) angles in a trapezoid are supplementary. Thus, we know that if , then . Since we are told that  and  are paired and trapezoid  is isosceles,  must also equal .

Example Question #2 : How To Find An Angle In A Trapezoid

Q2

In the isosceles trapezoid above, 

 .  and .

In degrees, what is the measure of  ?

Possible Answers:

Correct answer:

Explanation:

To find the measure of angle DAC, we must know that the interior angles of all triangles sum up to 180 degrees. Also, as this is an isosceles trapezoid,  and  are equal to each other. The two diagonals within the trapezoid bisect angles  and  at the same angle.

Thus,  must also be equal to 50 degrees.

Thus, .

Now that we know two angles out of the three in the triangle on the left, we can subtract them from 180 degrees to find :

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