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8. Introduction to Trigonometry
easy
$\sin ^{2} 30-\tan 45+\cos ^{2} 60-\cot 90\,= ........$
A
$-\frac{1}{2}$
B
$1$
C
$\frac{3}{2}$
D
$2$
Solution
$\sin ^{2} 30-\tan 45+\cos ^{2} 60-\cot 90$
$=\left(\frac{1}{2}\right)^{2}-1+\left(\frac{1}{2}\right)^{2}-0$ $\left(\because \sin 30=\cos 60=\frac{1}{2}\right.$ and $\left.\tan 45=1\right)$
$=\frac{1}{4}-1+\frac{1}{4}=\frac{1}{2}-1=-\frac{1}{2}$
Standard 10
Mathematics
