Question

If sinA=4/5 solve sin2A, cos2A and tan2A​

Answer 1

Explanation:

1) if m(∠A)∈[0;90°), then

`cos(A)=√(1-sin^2A) =(3)/(5);`

`sin2A=2sinAcosA=2*(3)/(5) *(4)/(5)=(24)/(25);`

`cos2A=cos^2A-sin^2A=(9)/(25)-(16)/(25)=-(7)/(25);`

`tan2A=(sin2A)/(cos2A)=-((24)/(25))/((7)/(25))=-(24)/(7).`

2) if m∠A∈[90°;180°), then

cos(A)=-0.6;

sin2A=-0.96;

cos2A=-0.28;

tan2A=-24/7.