Question

11. The value of sin 60° cos 30° + sin 30° cos 60° is
​

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:

sin 60 = root 3/2

cos 30 = root 3/2

root 3/2×root 3/2 = 3/4

sin 30 =1/2

cos 60=1/2

3/4+1/4 =1