How do you prove #cos(pi/2-theta)=sin theta #?

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Answer 1 · 2016-04-16T23:05:44

See below

LHS =left hand side, RHS =right hand side

Use formula #cos(A-B)=cosAcosB+sinAsinB#

LHS #=cos (pi/2)cos theta + sin (pi/2)sin theta#

#=0 xx cos theta + 1 xx sin theta#

#=0+sin theta #

#=sin theta #

#=RHS#