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If ysin⁡45∘cos⁡45∘=tan⁡245∘−cos⁡230∘, then y=… y \sin 45^\circ \cos 45^\circ = \tan ^245^\circ - \cos^2 30^\circ, \text{ then } y = \ld
Question

If ysin45cos45=tan245cos230, then y= y \sin 45^\circ \cos 45^\circ = \tan ^245^\circ - \cos^2 30^\circ, \text{ then } y = \ldots​​

A.

-1/2.

B.

1/2

C.

-2

D.

2

Correct option is B

Given:  ysin45cos45=tan245cos230 y \sin 45^\circ \cos 45^\circ = \tan 2 \cdot 45^\circ - \cos^2 30^\circ

Solution:

We know,

sin45=12,cos45=12\sin 45^\circ = \frac{1}{\sqrt{2}}, \quad \cos 45^\circ = \frac{1}{\sqrt{2}} , tan45=1,cos30=32,\tan 45^\circ = 1, \quad \cos 30^\circ = \frac{\sqrt{3}}{2}, \quad​​

Now,

y×12×12=134y \times \frac{1}{\sqrt{2}} \times \frac{1}{\sqrt{2}} = 1 - \frac{3}{4} ​​​​

y×12=134y \times \frac{1}{2} = 1 - \frac{3}{4}​​

y2=14\frac{y}{2} = \frac{1}{4}​​

y = 24\frac{2}{4}

y =12 \frac{1}{2}

Thus, the correct answer is (b).

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