Question

The angle 01 is located in quadrant IV, and sin(01)= -10/13 what is the value of cos(01)?

Answer 1

The Pythagorean identity is

`\cos ^2\theta=1-\sin ^2\theta`

we have

`\sin (\theta_1)=-(10)/(13)`

we substitute the values in the identity

`\cos ^2(\theta_1)=1-(-(10)/(13))^2`
`\cos (\theta_1)=\sqrt[]{1-(-(10)/(13))^2}=\frac{\sqrt[]{69}}{13}`