Question

упростите выражение (1+tg2a)*cos2a

Answer 1

$(1+tg^2a)*cos^2a=(1+ frac{sin^2a}{cos^2a})*cos^2a=( frac{cos^2a+sin^2a}{cos^2a})*cos^2a= \ \ cos^2a+sin^2a=1$

$(1+tg2a)*cos2a=(1+ frac{sin2a}{cos2a})*cos2a=( frac{cos2a+sin2a}{cos2a} )*cos2a= \ \ sin2a+cos2a$