Question

What is the length of missing side JK? Round Answer to nearest tenth please.

Answer 1

Given:

Triangle LJK.

LJ = 89 in, LK = 28 in and m∠L = 42°

To find:

The length of missing side JK.

Solution:

LJ = k = 89

LK = j = 28

JK = l = ?

Using law of cosine:

$l^{2}=j^{2}+k^{2}-2 jk \cdot \cos L$

Substitute the given values.

$l^{2}=28^{2}+89^{2}-2 \cdot 28 \cdot 89 \cdot \cos 42^\circ$

$l^{2}=784+7921-4984 \cdot (0.7)$

$l^{2}=784+7921-4984 \cdot (0.7431)$

$l^{2}=784+7921-3703.6$

$l^{2}=5001.4$

Taking square root on both sides.

$l=70.7$

The length of the missing side is 70.7 in.