Question

Solve a triangle when A=40°, C=70°, and a=20.

Answer 1

The answer is (c) ⇒ B = 70° , b = 29.2 , c = 29.2

Explanation:

∵ m∠A = 40° , m∠C = 70°

∴ m∠B = 180 - (40 + 70) = 70°

By using sin rule

∵
`(a)/(sinA)=(b)/(sinB)=(c)/(sinC)`

∵ a = 20

∵
`(20)/(sin40)=(b)/(sin70)`

∴
`b=(20sin70)/(sin40) =29.2`

∴
`(20)/(sin40)=(c)/(sin70)`

∴
`c=(20sin70)/(sin40)=29.2`

∴ m∠B = 70° , b = 29.2 , c = 29.2