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msingh
prove that the length of the perpendicular from the origin to the straight line joining the two points having coordinates ( a cos alpha, a sin alpha) and (a cos beta, a sin beta) is a cos { ( alpha + beta)/2}.
First find equation of the line passing through ( a cos alpha, a sin alpha) and (a cos beta, a sin beta)
may i know ur calculated eqution for those 2 given points\[(a \cos \alpha , a \sin \alpha) , (a \cos \beta ,a \sin \beta)\]
(y - asinα)=[(asinβ-asinα)/(acosβ-acosα)]*(x-acosα)
if u need more help then plz ask