The average value of cosx on the interval [-3, 5] is

To get the value of cosX on the interval [-3,5] we proceed as follows:

Using Pythagorean theorem we shall obtain the hypotenuse as follows:

c²=a²+b²

thus

c² = (-3) ²+5²

c² = 34

c = √34

hence:

cos X = (adjacent) / (hypotenuse)

cos X=-3/√34