I find the easiest way to solve these is to sketch them first (I'm a visual learner;) We get a nice right-angled triangle, with the right-angle at B. The formula for the area of a triangle is 1/2 * base* height or (base * height)/2.
We can use BC or AB as the base.
If we use BC as the base, the length is 9-4 or 5. The height is 6-2 or 4.
We can now but the base and the height in the formula to figure out the area.
Good luck.
Paul
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