Finding the area of a triangle.

We've got a good  challenge for you today but you need to remember how to find the area of  a triangle so look at this video if you have forgotten. Click here to remind yourself. You also have to remember our work on the radius of a circle.

Here is the challenge:

Answers tomorrow, in the meantime, post your answer in the comments.

Tuesday Update - the answer is 24.5 cm2

Here's how we worked it out.