Stuck here, any takers?
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A point on the terminal side of angle θ, is given. Find the exact value of the indicated Trigonometric Function of θ.
(9,12); Find the sin θ.
To expand a little on what princeps showed you, if you plot the point (9, 12) in the coordinate plane, and drop a perpendicular to the x-axis and a line back to the origin, you will have formed a right triangle. You will note that x = 9 and y = 12.
You need to find r, the length of the hypotenuse. Use the Pythagorean Theorem. $\displaystyle r^2=x^2+y^2$. We determine that r = 15.
Since we know that sin of an acute angle in a right triangle is the ratio of the opposite side of the angle divided by the hypotenuse, we can say:
$\displaystyle \sin \theta = \frac{y}{r}= \frac{12}{15}=\frac{4}{5}$