Question

What is cos A?

Answer 1

Answer:

$cos A = \frac{5}{13}$

Step-by-step explanation:

The given triangle, ∆ABC is a right triangle.

To find cos A, we'd need to apply the trigonometric ratio formula, which is cos A = adjacent length/hypotenuse length

From the ∆ given,

AC = adjacent = 15,

BC = opposite = 36

We are not given the hypotenuse length AB.

==>Find the hypotenuse length AB, using the Pythagorean theorem formula:

c² = a² + b²

AB² = 15² + 36² = 225 + 1296 = 1521

AB = √1521

AB = 39

==>Find cos A:

cos A = adjacent/hypotenuse

$cos A = \frac{adjacent}{hypotenuse}$

Adjacent = AC = 15

Hypotenuse = AB = 39

$cos A = \frac{15}{39}$

$cos A = \frac{5}{13}$