0
No. Tan(x)=Sin(x)/Cos(x)
Sin(x)Tan(x)=Sin2(x)/Cos(x)
Cos(x)Tan(x)=Sin(x)
sin(x) + cos(x) = sqrt(2) · sin(45°+x)
x = sin-1 (4/15)
( sin -1 is [SHIFT] [sin] on a calculator )
= 15.5
22.20366435
sin^-1(0.3779)
0. sin 2x = cos 3x
1. sin 2x = sin (pi/2 - 3x) [because cos u = sin (pi/2 - u)]
2. [...]