Question

maths 1st sum 3rd bit

Answer 1

Hope u like my process
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$\bf \underline{L. H. S} \\ \\ = > \bf \: \cos(a - b) \\ \\ = \cos(60 - 30) = \cos(30) \\ \\ = \bf \frac{ \sqrt{3} }{2} \\ \\ \bf \underline{R. H. S} \\ \\ = > \bf \: \cos(a) \cos(b) + \sin(a) \sin(b) \\ \\ = \cos(60) \times \cos(30) + \sin(60) \times \sin(30) \\ \\ = ( \frac{1}{2} \times \frac{ \sqrt{3} }{2}) + ( \frac{ \sqrt{3} }{2} \times \frac{1}{2} ) \\ \\ = \frac{ \sqrt{3} }{4} + \frac{ \sqrt{3} }{4} = \bf \frac{ \sqrt{3} }{2}$

Hence

L.H.S = R.H.S

(PROVED)

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