Question

Chapter - Trigonometry -2
Class -11 th
Prove the following :
vi) Sin20° Sin40° Sin60° Sin80° = 3/16

Give explanation of each step .​

Answer 1

Answer:

we know the identity that:

(sin theta)(sin(60+theta)(sin(60-theta) =1/4sin3theta

where theta is 20°

thus,

sin60° × 1/4 sin (3×20°}

√3/2 × 1/4 × √3/2

= 3/16

thus , proved

Answer 2

Question ⤵

Prove the following :

vi) Sin20° Sin40° Sin60° Sin80° = 3/16

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We know the identity that:

(sin theta)(sin(60+theta)(sin(60-theta) =1/4sin3theta

where theta is 20°

thus,

sin60° × 1/4 sin (3×20°}

√3/2 × 1/4 × √3/2

= 3/16

thus , proved

Thanks..