Answer
$r=-70.0 cm$
Work Step by Step
To find the radius of curvature, use the equation $$R=2f$$ "The distance between the focal point and the mirror" is defined as the focal length. Therefore, the focal length is $35cm$. Since the mirror is convex, the value of the focal length is negative. Substituting this value into the equation yields $$R=2(-35cm)=-70.0cm$$