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.