first of all you have to work out one of the angles using the formula d^2=f^2+g^2 - 2fgCosD rearranged so 6^2 = 9^2 + 11^2 - 2x9x11xCosD 36= 81+121 - 198xCosD -166 = -198CosD -166/-198 = 0.83838384 = Cos D Cos^-1 x 0.8383838384 = 33.030239731 = angle D the formula to work out the area is 1/2fgSinD 0.5 x 9 x 11 x Sin33.030239731 = 26.981538957 the area therefore of DFG to the nearest unit is 27 ONE FINAL TIP with numbers with decimals do not round until the very end otherwise your answer will be distorted
