Please solve question number 12

Please solve question number 12 11. Provc that for the curve y = c cos h —, thc radius of curvatwe at any point varies as the square of the ordinate at that 12 Prmethattheradiusofcuwa1ureoftheconicax2 + by2 =lvariesasthecubeofthc length of thenonnal, 13. Show that in the parabola v 2 = 4ax, the radius of cunature at any m•intP is twice the parl of the normal intercepted t-*tween the cune and the directrix. 14. Show that the radius of culNature for the curve y z a cos h — is equal to the normal intercepted between