-1 + cosec kuadrat 45 derajat = cotan kuadrat 45 derajat

- 1 + csc²45° = cotan²45°
-1 + (akar2)² = 1²
-1 + 2 = 1
1 = 1

Bab Trigonometri
Matematika SMA Kelas X

cara pertama, identitas
-1 + cosec² a = cot² a

cara ke dua
-1 + cosec² 45°
= -1 + (1/(sin 45°))²
= -1 + (1/(1/√2))²
= -1 + √2²
= -1 + 2
= 1

cotan² 45° = (1/(tan 45°))²
cotan² 45° = (1/1)²
cotan² 45° = 1

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