Orient the triangle so that the base is 6.
You cut the triangle in half, leaving you with a pair of right triangles. The base of each rt triangle is 3, and the hypotenuse is 5.
Now just apply that really old guy's theorem: a^2 + b^2 = c^2
You back into the height by taking (c)5^2 less (b)3^2 (25-9), which is 16. The sqrt of 16 is 4. That's your height.
(4^2)+(3^2)=5^2
Area=1/2bh
= .5 * 6 * 4
= 12sq whatevers
My son's school hit that in 5th here in CA.
Ok, I can see that now, and make it work, although I forget how to determine which is A and B and C so as to get the formula in the right order. DS8 is almost done with 7th grade math in ALEKS and says he has a topic on that but hasn't done it yet, and it hasn't shown up in anything up to that.
