Question

докажите тождество ctgt * sin^2t=(tgt+ctgt)^-1

Answer 1

1) ctgt*sin^2t=(cost/sint)*sin^2t=cost*sint

2) (tgt+ctgt)^-1=((sint/cost)+cost/sint))^-1=((sin^2t+cos^2t)/(cost*sint))^-1=(1/(cost*sint))^-1=cost*sint

1)=2)     cost*sint=cost*sint