Buktikan identitas trigonometri :

ID Trigonometri

no. 1

sec a = 1/cos a

sin² a + cos² a = 1

•

(sec² θ – 1 )/ sec² θ

= (sec² θ / sec² θ) – (1/sec θ)

= 1 – cos² θ

= sin² θ

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no. 2

csc a = 1/sin a

•

(sec B – cosec B) (sin B + cos B)

= sec B sin B + sec B cos B – cosec B sin B – cosec B cos B

= (sin B/cos B) + (cos B/cos B) – (sin B/sin B) – (cos B/sin B)

= tan B + 1 – 1 – cotan B

= tan B – cotan B

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