Jika diketahui sin a = 1/5V2, hitunglah A cos a B buktikan bahwa sin2 a+cos2 a=1

Bab Trigonometri
Matematika SMA Kelas X

sin a = (1/5) √2

A] cos a = √(1 - sin² a)
cos a = √(1 - ((1/5) √2)²)
cos a = √(1 - (2/25))
cos a = √((25 - 2)/25)
cos a = √(23/25)
cos a = (1/5) √23

B] sin² a + cos² a = 1
((1/5) √2)² + ((1/5) √23)² = 1
2/25 + 23/25 = 1
25/25 = 1
1 = 1

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