Question

Известен tg a=4/3 найти sin b

Answer 1

sin b = cos a

tg 3/4 = ctg 4/3

1+ctg^2 a = 1/cos^2 a

1+9/16=1/cos^2 a

25/16=1/cos^2 a

cos^2 a=16/25

cos a = 4/5

cos a = 0.8