Question

2 cos Sq 30 dgree - 1​

Answer 1

Answer:

Step-by-step explanation:

2cos^2 30degree - 1 = 1 - 2sin^2 30degree =cos 60 degree.

(putting the value of cos^2 30 degree and sin^2 30degree and 60 degree.)

=2×((square root of 3)/2)^2-1=2×(1/2)^2=1/2

{putting the value of (square root of 3/2)^2}

=2×3/4-1=2×1/4=1/2

=3/2-1=2×1/4=1/2

=1/2=1/2=1/2

[hence proved]

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Answer 2

Answer:

Step-by-step explanation:

$2cos^230 -1$

we know,

$cos30=\sqrt{3} /2$

Now,

$(\sqrt{3}/2 )^{2} -1$

$=\frac{3}{4} -1$

$= \frac{3-4}{4}$

$=-1/4$