Question

if 2Sin A-1=0 then show that Sin 3A=3 Sin A- 4 sin^3 A

Answer 1

Solution:

2Sin(A -1) = 0

SinA = 1/2

SinA = Sin30°

=> A = 30°

Now,

LHS : Sin 3A = Sin 90° = 1

RHS : 3SinA - 4Sin³A

= 3Sin30°-4Sin³30°

= 3×(1/2)-4(1/2)³

= 3/2-1/2 = 1

LHS = RHS

Hence Proved.

Answer 2

Answer:

Step-by-step explanation:

Solution:

2Sin(A -1) = 0

SinA = 1/2

SinA = Sin30°

=> A = 30°

Now,

LHS : Sin 3A = Sin 90° = 1

RHS : 3SinA - 4Sin³A

= 3Sin30°-4Sin³30°

= 3×(1/2)-4(1/2)³

= 3/2-1/2 = 1

LHS = RHS

Hence Proved.

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