If angle theta is 135o evaluate cos theta - JAMB Mathematics 2012 Question
If angle \(\theta\) is 135o, evaluate cos\(\theta\)
A
\(\frac{1}{2}\)
B
\(\frac{\sqrt{2}}{2}\)
C
\(-\frac{\sqrt{2}}{2}\)
D
\(-\frac{1}{2}\)
correct option: b
\(\theta\) = 135o
Cos 135o = Cos(90 + 45)o
= cos90ocos45o - sin90osin45o
= 0cos45o - (1 x \(\frac{\sqrt{2}}{2}\))
= \(-\frac{\sqrt{2}}{2}\)
Cos 135o = Cos(90 + 45)o
= cos90ocos45o - sin90osin45o
= 0cos45o - (1 x \(\frac{\sqrt{2}}{2}\))
= \(-\frac{\sqrt{2}}{2}\)
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