Jika tan a =2/3 maka tentukan nilai sin a dan cos a

Tan a = ⅔
Tan²a = (⅔)²
Tan²a - 1 = 4/9 - 1
1 / Cos²a = -5/9
Cos²a = -9/5
Cos a = √(-9/5)
Cosa = -3/5 √5

sina= √(1-cos²a)
=√(1+9/5)
= √(14/5)

Tan a = 2/3 = de/sa => mi = √(2^2 + 3^2) = √(4 + 9) = √13
Sin a = de/mi = 2/√13 = (2/13) √13
Cos a = sa/mi = 3/√13 = (3/13) √13