Question

if SinA+CosA=1√2 find 4sinA.CosA​

Answer 1

Step-by-step explanation:

$( \sin( \alpha ) + \cos( \alpha ) ) ^{2} = (\frac{1}{ \sqrt{2} } ) ^{2} \\ \sin ^{2} ( \alpha ) + \cos {}^{2} ( \alpha ) + 2 \sin( \alpha ) \cos( \alpha ) = \frac{1}{2} \\ 1 + 2 \sin( \alpha ) \cos( \alpha ) = \frac{1}{2} \\ 2 \sin( \alpha ) \cos( \alpha ) = ( \frac{ - 1}{2} ) \\ 2 \times ( 2 \sin( \alpha ) \cos( \alpha ) = 2 \times ( \frac{ - 1}{2} ) \\ 4 \sin( \alpha ) \cos( \alpha ) = ( - 1)$

if it is 1_/2 then use the same method thank you