Question

设Sin(a+pai/2)=1/4,且a是锐角.求Sina,求Tan(a+pai/4)

Answer 1

Sin(a+π/2)=sin(π/2-(-a))=cos(-a)=cosa=1/4

sina=√15/4

tana=√15/15

tan(a+π/4)

=(tana+tanπ/4)(1-tanatanπ/4)

=(√15/15+1)/(1-√5/15)

=(√15+15)/(15-√15)