Question

Let r1 and r2 be unit vectors in the xy plane making angles a and R with the positive x-axis.
(a) Prove that r1= cos a i + sin a j, r2 = cos (b i + sin b j .
(b) By considering r1. r2 prove the trigonometric formulas
cos (a - b) = cos a cos b + sin a sin b, cos (a + b) = cos a cos b - sin a sin b

where a= alpha, b= beta

Answer 1

Answer:

the length of a class 1 lever is 2 m calculate its mechanical advantage if the philtrum is at a distance of 40 cm from the point