Tangents from External Point
UNCHECK the first box to remove the lengths of AC and AB. If you now had to PROVE they were equal, WITHOUT checking the Step 1 box, what do YOU think should be the FIRST STEP...?
Check off STEP 1 - were you correct? WITHOUT checking off the What I Know box, write down what you now know that will be helpful.
Click on Step 2 - you now have all you need to prove that AC = BC. How do you do that? Hint: What information do you need to prove that two right-angled triangles are congruent?
The line joining the external point and the centre of the circle bisects the angle between the tangents. Check the box to see the angles. Is it obvious why?