Figure cdef is a parallelogram. What is the value of r?

Solution:

We know that

A parallelogram is a quadrilateral having two pairs of parallel sides. 

The opposite sides of a parallelogram are of equal length and the opposite angles of a parallelogram are of equal measure.

By using the property of a parallelogram which states that the length of any two opposite sides are equal. 

CF = DE

10r - 20 = 6r

By further simplification

10r - 6r = 20

4r = 20

Dividing both sides by 4

r = 5

Therefore, the value of r is 5.

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Figure cdef is a parallelogram. What is the value of r?

Summary:

Figure cdef is a parallelogram. The value of r is 5.