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Bab Trigonometri
Matematika SMA Kelas X

a] cos x . cosec x . tan x
= cos x . 1/sin x . sin x / cos x
= 1

b] cos x . cot x + sin x
= (cos x . cos x / sin x) + sin x
= (cos² x + sin²x) / sin x
= 1/sin x
= cosec x

c] (sin x /(1 + cos x)) + (sin x / (1 - cos x))
= (sin x - sin x cos x + sin x + sin x cos x)/(1 - cos² x)
= 2 sin x / (sin² x)
= 2 . cosec x

d] (sin a + cos a)² + (sin a - cos a)²
= sin² a + 2 sin cos a + cos² a + sin² a - 2 sin a cos a + cos² a
= 2

e] (cosec a - cot a) (1 + cos a)
= cosec a + cos a cosec a - cot a - cos a cot a
= 1/sin a + cos a / sin a - cot a - cos a . cos a/sin a
= (1 - cos² a)/sin a
= sin² a / sin a
= sin a