# Let tan x = 2.4, sin y = 0.6, and both x and y be between 0° and 90°. Then cos(x + y) equals?

##### 2 Answers

May 12, 2018

#### Explanation:

May 13, 2018

cos (x + y) = - 0.246

#### Explanation:

Use trig identity:

cos (x + y) = cos x.cos y - sin x.sin y (1)

First, find cos y knowing sin y = 0.6

Next, find sin x and cos x, knowing tan x = 2.4.

Replace all numeric values into equation (1), we get:

Check by calculator.