A=(x,y)A = (x, y) A=(x,y)
AT=(y,x)A^T = (y, x) AT=(y,x)
cosθ=a⃗∗b⃗∣∣a⃗∣∣∗∣∣b⃗∣∣;cos\theta = \frac{ \vec{a} * \vec{b}}{||\vec{a}||* ||\vec{b}||}; cosθ=∣∣a⃗∣∣∗∣∣b⃗∣∣a⃗∗b⃗;
consθ=a^∗b^cons\theta = \hat{a} * \hat{b} consθ=a^∗b^