Question

prove that cos 105 + cos 15= sin 75-sin 15 ​

Answer 1

Answer:

hence proved

Step-by-step explanation:

cos 105 = cos 90+15

             = -sin15

cos 15 = cos 90-75

           = sin75

put the values and you have the answer

Answer 2

Answer

cos 105 + cos 15

= sin ( 90 - 105 ) + sin ( 90 - 15 ) [°.° cos A = sin ( 90 - A )]

= - sin 15 + sin 75

= sin 75 - sin 15

Hence Proved