Question

what are the values of ab and de in parallelogram abcd?
ab = 13 (type an integer or a decimal)
de = \square (type an integer or a decimal)

Explanation:

Step1: Use parallelogram side property

In parallelogram \(ABCD\), opposite sides are equal: \(AB = CD\). Wait, no—correction: \(AB = CD\) is wrong, actually \(AB = CD\) and \(AD = BC\). \(BC = 21\), so \(AD = 21\). We know \(AE = 17\), so \(DE = AD - AE\).

Step2: Calculate length of DE

\(DE = AD - AE = 21 - 17\)

Answer:

\(AB = 13\)
\(DE = 4\)