Question

Using the given figure, find out which of the following option is correct.

• A. $sin\theta =\frac{BC}{AC}$
• B. $sin\alpha =\frac{BC}{AC}$
• C. $sin\theta =\frac{AB}{AC}$
• D. $sin\alpha =\frac{AC}{AB}$

Answer 1

The correct option is A

$sin\theta =\frac{BC}{AC}$

Observe that the side AC is the hypotenuse as it is opposite to the right angle.

Sine of an angle is the ratio of the side opposite to it and the hypotenuse.
Side BC is opposite to the angle $\theta$.
So,
$sin\theta$ = $\frac{BC}{AC}$.

Similarly, Side AB is opposite to the angle $\alpha$.
So,
$sin\alpha =\frac{AB}{AC}$.