posted by molly .
ABC is a piece of wire bent so that straight portions AB and BC, whose lenghts are 3 inches and 4 inches, are at a right angle. The end A is fixed. What is the locus of C?
I just don't know how to start!
Did you make a sketch?
Doesn't ABC form a right-angled triangle?
How long is AC ? (use Pythagoras to find it is always 5 inches)
So as A is fixed, isn't AC always 5 as the triangle is rotated about A ?
So I see a circle with centre at A and a radius of AC = 5.