Question

The lengths of the three sides of a triangle (not necessarily a right triangle) are 1.98 meters, 7.09 meters and 5.49 meters. What is the cosine of the angle opposite the side of length 5.49 meters?

Answer 1

Here we need to use the cosine rule to find the angle opposite to side of lenght 5.49 meters.

Let us assume A is the angle opposite to side of length 5.49 meters.

Formula for finding angle is given below

So calculating this we get,

Cos(A) = 0.8565

To find the angle A we need to apply inverse cosine function on both sides.

So we get cos^-1 (cos(A)) = cos^-1 (0.8565)

That is A = cos^-1 (0.8565) = 31.0741

Hence cosine angle opposite to the side of length 5.49 meters is 31.0741

Hope this will help you.

Thanks.