Open the control panel on the upper right.
Click Viewpoint and "Allow change" to enable moving around, then left click and drag to change viewing angle.
Right click and drag to change viewing position.
Center click or scroll to change viewing distance.
Change the vector with its the control menu.
C is the hypotenuse, A is the vertical side, B is the horizontal side, and θ is the angle from B to C.
C = √(A2 + B2).
tan(θ) = A/B
sin(θ) = B/C
cos(θ) = A/C