The area of a triangle is hb/2, we are told the base but not the side lengths. The side length can be found using the pythagorean theorem.
s^2=(b/2)^2+h^2
The height can be found from the area because:
A=bh/2 so
h=2A/b then our pythagorean identity becomes:
s^2=(b/2)^2+(2A/b)^2
s^2=b^2/4+4A^2/b^2 or a little more neatly
s^2=(b^4+15A^2)/(4b^2), we were told A=150 and b=12 so
s^2=358236/576
s=√(358236/576) ft
s≈24.939 to nearest thousandth (which means that they actually rounded wrong because that's...
s≈24.9 to nearest tenth (they must have made earlier rounding somewhere in the earlier calculations, that's why you use symbols until the final calculation :P)
a) 3*1.99 I estimated 3*2=6 1*3.99=4 2*1.29=2*1.25=3 1.25*1 .20*3=.75 6+4+3+1+.75= 14.75 $15 I just used easy to add numbers that made sense b) 3*1.99=4.97 + 1*3.99=3.99 + 2*1.29=2.58 + 1*1.25=1.25 + 0.20*3=0.60 = 13.39