#1**+10 **

Best Answer

This is just a Pythagorean right triangle in the 4th quad where x = 5, y = -12, and the hypoteneuse (r) = 13.

And the cosine is given by....

x/r = 5/13 = Answer (c)

CPhill Aug 1, 2014

#2**0 **

sorry .. but how do you know that it is in the 4th quad !

and why you put y=-12 !!

xvxvxv Aug 1, 2014

#3**+5 **

It's in the 4th quadrant because the angle "x" lies between -pi/2 and 0.....

And remember that in the 4th quadrant, x is positive and y is negative. And the tanx = y/x = -12/5

Does that make sense, xvxvxv ???

CPhill Aug 1, 2014

#4**0 **

I think that I forgot this information

if I not mistaken I think that there is a circle that illustrate this information !

do you know it .. ! because it will help me understand

xvxvxv Aug 1, 2014

#5**+5 **

Here's a pretty good page that will help you with this.....

http://www.themathpage.com/aTrig/unit-circle.htm

CPhill Aug 1, 2014