The velocity components of a particle moving in the `xy` plane of the reference frame K are equal to `v_x` and `v_y`. Find the velocity `v^'` of this particle in the frame K in the positive direction of its x axis.

Explanation

By the velocity addition formula
`v_x'=(v_x-V)/(1-(Vv_x)/(c^2)), v_y'=(v_ysqrt(1-V^2//c^2))/(1-(v_xV)/(c^2))`
and `v^'=sqrt(v_x'^2+v_y'^2)=(sqrt((v_x-V)^2+v_y^2(1-V^2//c^2)))/(1-(v_xV)/(c^2))`