Question

Question in screenshot

Answer 1

∠ A ≈ 24.1°

Explanation:

Using the law of sines , then

`(9)/(sinA)` =
`(21)/(sin72)` ( cross- multiply )

21 × sinA = 9 × sin72° ( divide both sides by 21 )

sinA =
`(9sin72)/(21)` , then

∠ A =
`sin^(-1)` (
`(9sin72)/(21)` ) ≈ 24.1° ( to the nearest tenth )