Question

cos - sin =1 prove that cos + sin =+‐1​

Answer 1

cos-sin=1

-1(cos+sin)=1

cos +sin=1/-1

cos +sin=+-1

Answer 2

✰solution.

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let , cos A - sin A = x

given, cosA + sin A. = 1

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adding equation first and second' s squre

cos^2 A + sin^2A - 2.cosA.sinA➻ cos^2A+ sin^2A + 2 cosA . sin A = x^2 + 1

• or,. 2 [ sin^2A + cos^2A ] = x2 + 1

• or, 2 = x2 + 1

• or, x2 = 2 - 1

• or, x = +-√ 1

• so, cos A - sinA = +- 1