Value of cos A - sin A when A = frac{{5π }}{4}, is

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3.Trigonometrical Ratios, Functions and Identities

easy

The value of $\cos A - \sin A$ when $A = \frac{{5\pi }}{4},$ is

A

$\sqrt 2 $

B

$\frac{1}{{\sqrt 2 }}$

C

$0$

D

$1$

Solution

(c) $\cos A – \sin A = \cos \frac{{5\pi }}{4} – \sin \frac{{5\pi }}{4},\left( \because {A = \frac{{5\pi }}{4}} \right)$

$ = – \cos \frac{\pi }{4} + \sin \frac{\pi }{4} = – \frac{1}{{\sqrt 2 }} + \frac{1}{{\sqrt 2 }} = 0$.

Standard 11

Mathematics

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