由題幹得知A(3, 3),B(0, -1),C(4, 1),套用「行列式公式」如下: 三角形面積 = 1/2 x │[(0-3) x (1-3)] - [(4-3) x (-1-3)]│ = 1/2 x │[(-3) x (-2)] - [(1) x (-4)]│ = 1/2 x │6 - (-4)│ = 1/2 x │10│ = 5 →正解
由題幹得知A(3, 3),B(0, -1),C(4, 1),套用「行列式公式」如下: 三角形面積 = 1/2 x │[(0-3) x (1-3)] - [(4-3) x (-1-3)]│ = 1/2 x │[(-3) x (-2)] - [(1) x (-4)]│ = 1/2 x │6 - (-4)│ = 1/2 x │10│ = 5 →正解