Question

найти sina,cosa,tga,ctga если ctga/2=2

Answer 1

sin²a/2=1:(1+ctg²a/2)=1:(1+4)=1/5
cos²a/2=1-sin²a/2=1-1/5=4/5
cosa=2cos²a/2-1=8/5-1=3/5
sina=√(1-cos²a)=√(1-9/25)=4/5
tga=sina/cosa=4/5:3/5=4/5*5/3=4/3
ctga=1/tga=1:4/3=3/4