Question

Дано:ctga=3/4, ctgb=1/7, 0>a>п/2, 0<b<п/2. Найти a+b

Answer 1

tga=4/3  tgb=7
tg(a+b)=(tga+tgb)/(1-tga*tgb)=(4/3+7):(1-4/3*7)=25/3:(-26/3)=-1
a+b=-π/4+πn,n∈Z