Maths - Plot 3rd triangle point from slope angle

Question

I am making a game and I want the camera to be at the side of the two players, approximately 10 metres from the centre point between the two with rotation so it is 90 degrees from the line between the two, example picture here:

Answer 1

Let's coordinates of given points are (Ax,Ay), (Bx,By)

In vector form:

C = ( B+A )/2 + - 1/2 * Perpendicular( BA )

BAx = Bx-Ax ; BAy = By-Ay

BAPerpX = - BAy ; BAPerpY = BAx

Cx = Ax/2 +Bx/2 +- BAPerpX/2

Cy = Ay/2 +By/2 +- BAPerpY/2

Choose sign '+' or '-', and point C will lie to left or to right relative to AB line