jika tan a=2/3, maka cos a=

Kelas 10 Matematika
Bab Trigonometri

tan a = 2/3 → y/x

r = √(x² + y²)
r = √(3² + 2²)
r = √(9 + 4)
r = √13

cos a = x/r
cos a = (3/√13) . ((√13)/(√13))
cos a = (3/13) . √13