A triangle has sides a3 b5 c6 Find angle

A triangle has sides a=3, b=5, c=6. Find angle <C in degrees, rounded to two decimal places. Show your work.

Solution

Given data

A triangle has sides a=3, b=5, c=6

The cosine rule is

c^2 = b^2 + a^2 - 2ba cosc

Put all the values

cosc = ( b^2 + a^2 - c^2 )/2ba

cosc = (25 + 9 - 36)/30

c = cos^(-1){-2}/30

c = 93.82

Answer