Question

What is the formula?

Answer 1

74.2°

Explanation:

Given:

m<A = 60°

a = 18 cm

b = 20 cm

Required:

m<ABC = B

Solution:

Apply the sine rule

`(sin(B))/(b) = (sin(A))/(a)`

Plug in the values

`(sin(B))/(20) = (sin(60))/(18)`

Multiply both sides by 20

`(sin(B))/(20)*20 = (sin(60))/(18)*20`

`sin(B) = (sin(60)*20)/(18)`

`sin(B) = 0.96225`

`B = sin^(-1)(0.96225)`

`B = 74.2 degrees` (approximated to nearest tenth)