Question

who have little bit sense......... find the exact
value cos(135/2)

Answer 1

Answer:

-0.044227621 is the exact value.

Answer 2

To Find,

value cos(135/2)

Solution,

cos 135° = − cos45° = − $\frac{1}{\sqrt{2} }$

Cos 135° is an angle in the second quadrant.

In the second quadrant, cos is negative.

cosθ = $\frac{x}{r}$

cos 135 = cos (180−45) = − cos 45°

An angle of 45° is found in a right-angled triangle of sides 1:1:√2

cos45° =1√2

So , cos135°=−cos45°=−$\frac{1}{\sqrt{2} }$

Note that √2 is an irrational number and cannot be given as an exact decimal.-0.044227621 is the exact value.

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