Question

If sin(A-B)=sinAcosB - cosAsinB and cos(A-B)=cosAcosB + sinAsinB,find the value of sin15°and cos15°.​

Answer 1

Answer:

Use, A-B= required angle

A,B : angles whose values of trigonometric functions are known.

Sin(45-30)= sin 45°cos30°- cos 45°sin30°=1/root2(root3/2-1/2)

Answer 2

Step-by-step explanation:

Sin15° = Sin(45°-30°)

Sin45° * Cos30° - Cos45° * Sin30°

1/√2 * √3/2 - 1/√2 * 1/2

(√3 - 1)/ 2√2

Cos15° = Cos(45°-30°)

Cos45° * Cos30° + Sin45° * Sin30°

1/√2* √3/2 + 1/√2 * 1/2

(√3 + 1)/2√2