How do you verify #costhetacos(-theta)-sinthetasin(-theta)=1#?

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Answer 1 · 2016-11-17T21:09:11

see below

#cos theta cos(-theta)-sin theta sin(-theta)=1#

Use the odd and even property. That is, #cos (-theta)=cos theta# and #sin(-theta)=-sin theta#

Left Hand : #=cos theta cos(-theta)-sin theta sin(-theta)#

#=cos theta cos(theta)+sin theta sin(theta)#

#=cos^2 theta+sin^2 theta #

#=1#

#:.=# Right Side