sine and cosine rule help tah

hey can anyone help me with 15b???? thanks xx

1. Do you see what angle the radii make with the sides of the triangle AB, BC and AC?

2. What standard formula do you know for working out the area of a triangle?

3. In the formula, what would your radius represent? (Consider 1.)

hey can anyone help me with 15b???? thanks xx

First express the areas of the smaller triangles in terms of r e.g. for triangle IAB the area is 0.5 x 4 x r = 2r. (r is the perpendicular height since you can see a right-angle).

Then the sum of the areas of the smaller triangles is equal to the area of triangle ABC, which is your answer to (a).

If you're still stuck, can you post all your working?

Would it not be more difficult to do it the way you suggested?
The area of the constituent triangles of IBC wouldn't be so easy to work out because the radius doesn't intersect the midpoint of BC.

I'm not sure what you mean. Why would you need to work out the areas of the constituent triangles of IBC?