when sun rays meet ground at 30 deg

tan(60) = pole/orig shadow = sqrt(3)

orig shadow = pole/sqrt(3)

new shadow = 3 * orig shadow = 3*pole/sqrt(3) = pole*sqrt(3)

angle pole makes to ground when shadow is 3 times the first shadow

tan(x) = pole/new shadow = pole/pole*sqrt(3) = 1/sqrt(3)

thus x= 30 degrees