Question

Cứu mình mấy bài này với ạ ;-;

Answer 1

4:

a: cos^2a=1-(1/2)^2=1-1/4=3/4

=>\(cosa=\dfrac{\sqrt{3}}{2}\)

\(tana=\dfrac{1}{2}:\dfrac{\sqrt{3}}{2}=\dfrac{1}{\sqrt{3}}\)

\(cota=1:\dfrac{1}{\sqrt{3}}=\sqrt{3}\)

b: sin^2a=1-(3/4)^2=1-9/16=7/16

=>\(sina=\dfrac{\sqrt{7}}{4}\)

\(tana=\dfrac{\sqrt{7}}{4}:\dfrac{3}{4}=\dfrac{\sqrt{7}}{3}\)

\(cota=1:\dfrac{\sqrt{7}}{3}=\dfrac{3}{\sqrt{7}}\)