Posted by Dominique on .
Obtuse angles A and B are in standard position. Point P(3,4) is on the terminal arm of angle A. Point Q(9,12)is on the terminal arm of angle B. How are the measures of angles A and b related?
Please explain...

Math 
Reiny,
If you put P and Q on the same grid, did you notice that OQ is an extension of OP ?
so the angle formed by OP and OQ are the same
notice the hypotenuse of the smaller triangle is 5 by Pythagoras, and of the larger triangle it is 15
try this on your calculator:
2nd
cos
(
3÷5
)
= to get 126.8698...°
now try:
2nd
cos
(
9÷15
)
=
to get exactly the same angle of 126.8698...°