Use the Law of Cosines to find the measure of ∠A. Round to the nearest degree. a = 12, b = 5, c = 9

Use: a² = b² + c² – 2bc cos A

Solution given:

a = 12, b = 5, c = 9

We have

: a² = b² + c² – 2bc cos A

12²=5²+9²-2×5×9 cos A

12²-25-81=-90 cos A

cos A=38/-90

A=cos -1(-19/45)

A=115°

is a required answer.

395.84

step-by-step explanation:

2πrh+2πr²

2 (pie)(radius)(height)+2(pie)(radius)^2

after simplifying it i got: -36.25 as my answer. hope that !