sin(45-30)= sin 45 cos 30-cos 45 sin 30 =√2(√3- 1)/2

Angle of 37 degrees: When the three sides of a triangle are 3, 4 and 5 respectively, the triangle is a right triangle, and the corresponding angles are 37, 53 and 90 respectively.

So sina37=3/5 sina53=4/5.

75 degree angle; cos(45+30)= cos 45 cos 30-sin 45 sin 30 =√2(√3- 1)/2

sin(45+30)= sin 45 cos 30+cos 45 sin 30 =√2(√3+ 1)/2