Question

ABCD is a parallelogram. Determine the length of AD.

Answer 1

10

Explanation:

→ Equate both sides of the parallelogram as they are equal

2x = x + 5

→ Solve

x = 5

→ Resubstitute for the length AD

5 + 5 = 10

Answer 2

D) 10 units

Explanation:

Opposite sides of a parallelogram are congruent.

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setup

The relation between opposite sides tells you ...

BC = AD

2x = x +5

solution

x = 5 . . . . . . . subtract x from both sides of the equation

We want the length of AD, which is ...

AD = x +5 = 5 +5

AD = 10

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Additional comment

Often, it seems like the question is answered once the value of x is found. Here, finding the value of x is an intermediate step. The value of x is needed in order to be able to answer the question about the value of an expression involving x.