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An isosceles trapezoid has perimeter of 42 inches. Each of the congruent nonparallel sides is 5 inches long, and the trapezoid is 3 inches tall. How long are the two parallel sides?

a. 12 inches and 20 inches
b. 10 inches and 22 inches
c. 10 inches and 16 inches
d. 16 inches and 16 inches

off-topic
 Feb 26, 2019
 #1
avatar+100516 
0

Let the bottom base be the longer side

 

The non-parallel side and the height form a 3-4-5 right triangle

 

So....using symmetry....the bottom base is (4 + 4) =  8 units longer than the top base

 

So.....we have

 

x +( x + 8 )+ 5 + 5 = 42    simplify

 

2x +  18 = 42

 

2x = 24

 

x = 12  =  the top base

 

x + 8 =  20 = the bottom base

 

So  

 

a. 12 inches and 20 inches

 

cool cool cool

 Feb 26, 2019
edited by CPhill  Feb 26, 2019
 #2
avatar+100802 
-1

Draw the trapezoid.

Label the sides.

Divide it into 2 right angled triangles and one rectangle.

Find all three sides of the triangle.

 

Since the whole perimeter is 42 cm.

It is not too difficult to finish the question for yourself

Ask specific questions if you get stuck.

 Feb 26, 2019

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