jika tanX =2/3(x lancip) hitunglah cos2a dan sin 2a

TriGonoMetRi

tan x = y/x = 2/3
x lancip
r = √(2² + 3²) = √13

cos 2x
= 2 cos² x - 1
= 2 (x/r)² - 1
= 2 (3/√13)² - 1
= 18/13 - 1
= 5/13 ✔

sin 2x
= √(1 - cos² 2x)
= √(1 - 25/169)
= 12/13 ✔