Question

find the value of (cos 15°-sin 15°) ​

Answer 1

Step-by-step explanation:

cos (

$\cos( {45}^{0} - {30}^{0} ) = \cos( {45}^{0} ) \cos( {30}^{0} ) + \sin( {45}^{0} ) \sin( {30}^{0} )$

cos 15 = (√3/2√2) + (1/2√2) = (1 +√3) /2√2

similary,

Sin 15 = sin 45 cos 30 - sin 30 cos 45

= (√3/2√2) - (1/2√2) = (-1 + √3) / 2√2

cos 15 - sin 15 = [(1+ √3)/2√2] - [(-1+√3)/2√2]

= 2