If angle \(\theta\) is 135o, evaluate cos\(\theta\)
A
\(\frac{1}{2}\)
B
\(\frac{\sqrt{2}}{2}\)
C
\(-\frac{\sqrt{2}}{2}\)
D
\(-\frac{1}{2}\)
Verified Correct Answer: C.
Step-by-Step Mathematical Solution
\(\theta\) = 135o
Cos 135o = Cos(90 + 45)o
= cos90ocos45o - sin90osin45o
= 0cos45o - (1 x \(\frac{\sqrt{2}}{2}\))
= \(-\frac{\sqrt{2}}{2}\)
Source: Myschool Past Questions Archive (Record #27340)