Question

Find the cosine of R.

Write your answer in simplified, rationalized form. Do not round.

cos(R) =

Answer 1

`cos(R) = (√(15))/(5)`

Explanation:

To find the cosine of <R, apply the following trigonometric ratio formula:

`cos(R) = (adjacent)/(hypotenuse)`

Adjacent = 3

Hypotenuse = √15

Plug in the values into the formula

`cos(R) = (3)/(√(15))`

Multiply the numerator and denominator by √15 to rationalize.

`cos(R) = (3 * √(15))/(√(15) * √(15))`

`cos(R) = (3√(15))/((√(15))^2)`

`cos(R) = (3√(15))/(15)`

`cos(R) = (√(15))/(5)`