Question

Please help with finding the measure of EC? Given: AG and CI are common internal tangents of Circle H and Circle B, HG =7, ED=18, and ED=EF

http://img683.imageshack.us/img683/8950/diagram2i.png

Answer 1

since ED=EF both circles have the same radius
now HG=7 which is da radius of circle H
so radius of circle B is also 7, hence BD=7
EB=ED+DB
EB=18+7=25
the tangent to a circle makes a right angle with the radius of the circle, CB is the radius of circle B, CB=17
hence, triangle ECB is a right triangle, with the right angle being at C
so you can use the pythagoras theorem to find EC since you know the lengths of EB and CB

Answer 2

Thank you!

Answer 3

Did u mean 7 or 17?

Answer 4

sorry, CB=7

Answer 5

so what is EC?