Question

Q.4 cos 30º.cos 60° – sin 30°. sin 60° AT HET 1. 2 2. 1 3. 0 3 4. 2​

Answer 1

Answer:

Use sin(90

∘

−θ)=cosθ and cos(90

∘

−θ)=sinθ

and cos

2

θ+sin

2

θ=1

Now,

sin30

∘

⋅cos60

∘

+cos30

∘

⋅sin60

∘

=sin(90

∘

−60

∘

)⋅cos60

∘

+cos(90

∘

−60

∘

)⋅sin60

∘

=cos60

∘

⋅cos60

∘

+sin60

∘

⋅sin60

∘

=cos

2

60°+sin

2

60°=1

Answer 2

Answer:

0 us you are answer

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