Question

mike is looking at the roof of a new house from the front. he notices that the roof is triangular in shape with a base 11.2m. the left side is 6.7m long and makes an angle of 72 degree with the base of the roof. if this is the only known information, determine the angle the right side of the roof makes with the base of the roof to the nearest degree. be sure to first make a sketch

Answer 1

35°

Explanation:

From the sketch made, to obtain B we use the cosine angle formula :

We have 2 so des and an included angle

Cos B = (a² + c² - b²) / 2ac

First we obtain the side c

c² = a² + b² - 2ab CosC

c² = 11.2² + 6.7² - 2(11.7 * 6.7) * cos 72

c = 11.13

Using the value of c

Cos B = (a² + c² - b²) / 2ac

CosB = (11.2² + 11.13² - 6.7²) / (2*11.2*11.13)

Cos B = 204.4269 / 249.312

B = Cos^-1(204.4269 / 249.312)

B = 34.9°