Question

giúp e gấp với ạ

Answer 1

a: \(sinA=\sqrt{1-\dfrac{1}{2}}=\dfrac{1}{\sqrt{2}}\)

\(tanA=\dfrac{sinA}{cosA}=1\)

cot A=1/tan A=1

b: \(1+cos^2A=\dfrac{1}{tan^2A}=\dfrac{1}{3}\)

=>cos^2A=1-1/3=2/3

=>\(cosA=\dfrac{\sqrt{6}}{3}\)

\(sinA=\sqrt{1-cos^2A}=\dfrac{\sqrt{3}}{3}\)

cot A=1/tanA=1/căn3 

c: \(cosA=\sqrt{1-0.4^2}=\dfrac{\sqrt{21}}{5}\)

tan A=2/5:căn 21/5=2/căn 21

cot A=1/tanA=căn 21/2

d: 1+cot^2A=1/cos^2A

=>1/cos^2A=1+9/16=25/16

=>cosA=4/5

=>sin A=3/5

tan A=1:3/4=4/3