(A) √3 (B) 1/√3 (C) √3/2 (D) 1
(A) √3
As indicated by the inquiry,
![\[Sin\text{ }A\text{ }=\text{ }{\scriptscriptstyle 1\!/\!{ }_2}\text{ }\ldots \text{ }\left( 1 \right)\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-d4dc2f0ecde03459f70c875a82fb7123_l3.png "Rendered by QuickLaTeX.com")
We realize that,
NCERT Exemplar Class 10 Maths Chapter 8 Ex. 8.1 Question 2 … (2)
To discover the worth of cos A.
We have the condition,
![\[sin2\text{ }\theta \text{ }+cos2\text{ }\theta \text{ }=1\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-ea113bb3efd1927a99920ac1f455936d_l3.png "Rendered by QuickLaTeX.com")
In this way,
![\[cos\text{ }\theta \text{ }=\text{ }\surd \left( 1-sin2\text{ }\theta \right)\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-07f1cfa5f73b29fd442dc650dba8b133_l3.png "Rendered by QuickLaTeX.com")
Then, at that point,
![\[cos\text{ }A\text{ }=\text{ }\surd \left( 1-sin2\text{ }A \right)\text{ }\ldots \text{ }\left( 3 \right)\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-a74a0f584ca6f9876616885ed9f446e0_l3.png "Rendered by QuickLaTeX.com")
![\[cos2\text{ }A\text{ }=\text{ }1-sin2\text{ }A\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-781282335402596078f004f062daaf02_l3.png "Rendered by QuickLaTeX.com")
![\[cos\text{ }A\text{ }=\text{ }\surd \text{ }\left( 1-sin2\text{ }A \right)\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-139ecef73e1e7fa1b87a43f3ad4700d2_l3.png "Rendered by QuickLaTeX.com")
Subbing condition 1 of every 3, we get,
![\[cos\text{ }A\text{ }=\text{ }\surd \left( 1-1/4 \right)\text{ }=\text{ }\surd \left( 3/4 \right)\text{ }=\text{ }\surd 3/2\]](https://www.learnatnoon.com/s/wp-content/ql-cache/quicklatex.com-b85f88fc6e6218511bc91d7ea700c74f_l3.png "Rendered by QuickLaTeX.com")
Subbing upsides of transgression An and cos An in condition 2, we get
bunk A = (√3/2) × 2 = √3