Question

Cos 45 * cos 60 - sin 45 * sin 60​

Answer 1

Cos 60° cos 45° - sin 60° ∙ sin 45° …(i) By trigonometric ratios we know that,

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Answer 2

Step-by-step explanation:

QUESTION:

Cos 45 ×cos 60 - sin 45 × sin 60

SOME IMPORTANT VALUES:

cos 45 = 1/√2

cos 60 =1/2

sin 45 = 1/√2

sin 60 = √3 /2

SUBSTITUTING THE VALUES:

$\frac{1}{ \sqrt{2} } \times \frac{1}{2} - \frac{1}{ \sqrt{2} } \times \frac{ \sqrt{3} }{2} \\ \\ = \frac{1}{2 \sqrt{2} } - \frac{ \sqrt{3} }{2 \sqrt{2} } \\ \\ = \frac{1 - \sqrt{3} }{2 \sqrt{2} }$

HOPE IT HELPS.