Question

evaluate (sin 30 + sin 45)( cos 60 - cos 45)

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Answer 1

Answer:

$sol {n}^{n}$

$(sin30 {}^{0} +sin45 {}^{0})(cos60 {}^{0} - cos45 {}^{0} )$

$= ( \frac{1}{2} + \frac{1}{ \sqrt{2} } )( \frac{1}{2} - \frac{1}{ \sqrt{2} } )$

$= ( \frac{1}{2} {)}^{2} - ( \frac{1}{ \sqrt{2} } ) {}^{2}$

$= \frac{1}{4} - \frac{1}{2}$

$= \frac{1 - 2}{4}$

$= - \frac{1}{2}$