The sides of a triangle have lengths 2, 8, and 9. What kind of triangle is it?

Question

acute / right / obtuse

Answer 1

Given traingle we know three sides say a = 2, b = 8, c = 9

Use the law of cosines first to find one ofthe angles.

CosA = (b^2+c^2-a^2)/2bc

CosA = (64+81-4)/144

= 141/144

A = Cos^-1(0.979)

A = 11.762

CosB = (a^2+c^2-b^2)/2ac

= (4+81-64)/36

= 21/36

= 0.58

B = Cos^-1(0.58)

B = 54.54

C = 180-(A+B)

C = 180-(11.762+54.54)

C = 180-66.311

C = 113.68

Angles of triangle are 114,12,55.

Given traingle obtuse triangle.