Question

Find m PLEASE HELP 10 POINTS!!

Answer 1

(D). 17 in.

Explanation:

c² = a² + b² - 2abcosC

cosC =
`(a^2 + b^2 -c^2)/(2ab)`

m∠C =
`cos^(-1)` (
`(a^2 + b^2 -c^2)/(2ab)` )

m∠C =
`cos^(-1)` (
`(28^2 +18^2 -12^2 )/(2(28)(18))` )

m∠C =
`cos^(-1)` (
`(964)/(1008)` ) ≈ 17 in.

Answer 2

Use the cos rule

cos^-1(18^2+28^2-12^2 divided by 2*18*28

Which is 16.99 degrees, which is 17 (option d)