A car traveling with speed ( v ) around a curve of radius ( r ). Determine a formula for the angle which a road should be banked so that no friction is required.
a) ( θ = tan⁻¹(v²rg) )
b) ( θ = sin⁻¹(v²rg) )
c) ( θ = cos⁻¹(v²rg) )
d) ( θ = sec⁻¹(v²rg) )