Question

cos 68°cos 8°+sin 68°sin 8° with all solutin

Answer 1

Cos68°cos8°+sin68°sin8°

(cosAcosB+sinAsinB=cos(A-B))

Cos(68-8)

Cos60°

=1/2......

Answer 2

The vaue of cos 68°cos 8° + sin 68°sin 8° $=\dfrac{1}{2}$

Step-by-step explanation:

We have,

cos 68°cos 8° + sin 68°sin 8°

To find, the vaue of cos 68°cos 8° + sin 68°sin 8° = ?

∴ cos 68°cos 8° + sin 68°sin 8°

= cos (68° - 8°)

We know that,

The trigonometric identity,

$\cos (A - B)=\cos A\cos B + \sin A\sin B$

= cos 60°

$=\dfrac{1}{2}$

We know that,

$\cos 60=\dfrac{1}{2}$

Hence, the vaue of cos 68°cos 8° + sin 68°sin 8° $=\dfrac{1}{2}$