Question

упростите      - 4 sin^2 B + 3 cos^2 B + 5 ctgB * tgB

Answer 1

$-4sin^{2}beta+3cos^{2}beta+5tgbeta*ctgbeta=-4(1-cos^{2}beta)+3cos^{2}beta+5*1=$

$=-4+4cos^{2}cos^{2}beta+3cos^{2}beta+5=7cos^{2}beta+1$