Question

Find the cosine of R.

Answer 1

Answer:

$cos(R) = \frac{\sqrt{15}}{5}$

Step-by-step explanation:

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

$cos(R) = \frac{adjacent}{hypotenuse}$

Adjacent = 3

Hypotenuse = √15

Plug in the values into the formula

$cos(R) = \frac{3}{\sqrt{15}}$

Multiply the numerator and denominator by √15 to rationalize.

$cos(R) = \frac{3 \times \sqrt{15}}{\sqrt{15} \times \sqrt{15}}$

$cos(R) = \frac{3\sqrt{15}}{(\sqrt{15})^2}$

$cos(R) = \frac{3\sqrt{15}}{15}$

$cos(R) = \frac{\sqrt{15}}{5}$