Question

If the resultant of the two forces (P + Q) and (P – Q) is (P2 + Q2)

1/2 , then the angle

between them is given by​

Answer 1

Let resultant of two forces p and q is R , angle between R and p is 90°, let angle

between R and q is t . According to Lammi's theorem:-

p /sin t= q/sin90° = R/sin(270°-t).

or. p/sin t= q/1 => sin t = p/q………………..(1)

Angle between forces p and q is (90°+t). Therefore

cos (90+t)=- sin t , putting sin t = p/q from eqn. (1)

or. cos (90°+t) = -p/q.

or. (90° + t). = cos^-1(-p/q). Proved.

❀if you like my answer thanks please❀