# Math Help - trig help

1. ## trig help

the terminal arm of an angle in standard position passes through (3,11). Find the radian value of the angle in the interval [0,2pi], to the nearest hundredth.

i dont understand how to solve this problem. help is appreciated

2. Originally Posted by mzto
the terminal arm of an angle in standard position passes through (3,11). Find the radian value of the angle in the interval [0,2pi], to the nearest hundredth.

i dont understand how to solve this problem. help is appreciated

From the information we know that there is a point 3 away from start and in the y direction there is a point 11 away.

This will form a triangle with opposite 11 and adjacent 3. From there should be able to use a basic trig function to solve

Spoiler:
$tan(x) = \frac{11}{3}$

$x = tan^{-1}(\frac{11}{3}) =1.30$

3. why do i use tan and not the other trig ratios?

4. Because the (3,11) refers to an x and a y value. As it must be in the first quadrant that means the angle is measured from the horizontal (as is convention). If you sketch the diagram it is clearer.

You could use pythagoras theorem to find the hypoteneuse and use another ration but that could introduce rounding errors

5. ooh, okay thank you for your help ! (: