Question

sin(A-B)= sin A cos B - cosA sin B​

Answer 1

Answer:

(ii) Sin 75 = sin (45+30)

Sin ( 45 +30) = sin45 cos30 + cos45 sin30

                    = 1/√2 * √3/2 + 1√2* 1/2

                    = √3/2√2 + 1/ 2√2

                    = √3 +1 / 2√2

multiplying with √2,

(√3 + 1) * √2/ 2√2 *√2

= √6 + √2/ 4

(i) cos 15= cos(45-30)

  cos(45-30) = cos 45 cos30 - sin45 sin 30

                    = 1/√2 * √3/2 - 1√2 * 1/2

                    = √3 - 1/ 2√2

multiplying with √2,

(√3 - 1) * √2/ 2√2 *√2

= √6 - √2/ 4

hope it helps.... :)

Step-by-step explanation: