Class 8 / IIT Foundation Plus Maths / Multiples And Sub-Multiples / Proof For the Formulas - 1, 2, 3 And 4

Multiples and Sub multiples

Multiples and Sub multiples Proof : We know,  i) sin (A + B) = sinA . cosB + cosA . sinB     Put A = B     sin 2A = sinA cosA + cosA . sinA ii) cos (A + B