Question

If sinA=1/2 then find the value of 4cos^3A -3 cosA is

Answer 1

Sin A = 1/2
Sin 30 = 1/2
Therefore, A = 30
Now put the value of Cos30 in the question.

Answer 2

Answer:

The value of the following equation is Zero (0).

Step-by-step explanation:

Step 1:- According to the Trigonometric Table

Sin30° = 1/2

∴ According to the question

=> Sin A = 1/2

=> Sin A =Sin30°      [∵ Sin30° = 1/2, so we can replace 1/2 by Sin30° ]

=> A = 30°

Step 2:- Now, we will replace A with 30° from the equation,

=> 4Cos³A - 3CosA

we get,

=> 4Cos³30° - 3Cos30°

=> 4 × $(\frac{\sqrt{3} }{2} )^{3}$ - 3 × $\frac{\sqrt{3} }{2}$     [∵ Cos30° = √3/2]

=> 4 × $(\frac{\sqrt[3]{3} }{2} )$ - 3 × ( $\frac{\sqrt{3} }{2}$)    

=> $\frac{\sqrt[3]{3} }{2}- \frac{\sqrt[3]{3} }{2}$      [Here we have divided the first part of the equation with 4]

=> 0.

Hence the value of the equation is 0.