What does cos(arctan(-1))+sin(arc csc(-1))cos(arctan(1))+sin(arccsc(1)) equal?

1 Answer
Mar 10, 2016

cos(arctan(-1))+sin(arc csc(-1))=-1+-1/sqrt2cos(arctan(1))+sin(arccsc(1))=1±12

Explanation:

cos(arctan(-1))cos(arctan(1)) means cosalphacosα of an angle alphaα, where tanalpha=-1tanα=1. tanalpha=-1tanα=1 for alpha=(3pi)/4α=3π4 or alpha=(-pi)/4α=π4.

cos((3pi)/4)=-1/sqrt2cos(3π4)=12 and cos((-pi)/4)=1/sqrt2cos(π4)=12. Hence cos(arc tan(-1))=+-1/sqrt2cos(arctan(1))=±12

sin(arc csc(-1))sin(arccsc(1)) means sinbetasinβ of an angle betaβ, where cscbeta=-1cscβ=1.

cscbeta=-1cscβ=1 for beta=(3pi)/2β=3π2 and sin((3pi)/2)=-1sin(3π2)=1. Hence sin(arc csc(-1))=-1sin(arccsc(1))=1

Hence, cos(arctan(-1))+sin(arc csc(-1))=-1+-1/sqrt2cos(arctan(1))+sin(arccsc(1))=1±12