Question

1)find the value of sin (-840°)

Answer 1

sin(-180*5+60)
-cos60=1/2

Answer 2

Concept:

sin(nπ-θ)=sinθ where, n =odd natural no.s

sin(nπ-θ)=-sinθ where, n =even natural no.s

sin(nπ+θ)=-sinθ where, n =odd natural no.s

sin(nπ+θ)=sinθ where, n =even natural no.s

GIVEN:

sin(-840)

Find:

The value of sin(-840)

Solution:

sin(-180*5+60)

-cos60=1/2

Therefore, sin(-840)=1/2

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