Hi Mike,

question on Math Quiz 4 #9: I get the answer and the proposed solution (area of large triangle minus area of small triangle). But my daughter worked the problem differently and I think what she did was correct, but she got a slightly different answer and I can’t figure out exactly why.

Her solution: she used Pythag Theorem to get the hypot of small triangle: so 4^2 + 1^2 = c^2…. so c=Sqrt(17). This is base of large triangle. So A= 1/2 bXh, or 1/2 (sqrt 17)(8), she got 16.492.

When you’re finding the area of a triangle, the height you use needs to be perpendicular to the base you choose. In this case, drawing a segment from (2, 6) that is perpendicular to that base would require drawing it outside of the triangle.

If you’re going to use as your base (segment *BC*), then you need to use segment *AD* in the figure above as your height. This can be done easily with software, but I wouldn’t advise trying to do it by hand on test day.