If angle ? ? is 135o, evaluate cos?

Question 1 Report

If angle $θ$ is 135o, evaluate cos $θ$

\frac{1}{2}

\frac{\sqrt{2}}{2}

\frac{\sqrt{2}}{2}

\frac{1}{2}

Answer Details

$θ$ = 135o
Cos 135o = Cos(90 + 45)o
= cos90ocos45o - sin90osin45o
= 0cos45o - (1 x $\frac{\sqrt{2}}{2}$ )
= $- \frac{\sqrt{2}}{2}$