can u please provide solution for 6.40 3.A crank rocker is to be used in a windshield-wiping mechanism. The wiper must oscillate 80°. The time for the forward and return stroke for the wiper is the same. If the base link (r1) of the mechanism is to be 10 cm long, determine the lengths of the other links (r3 and r4). Sketch the mechanism to scale. Assume suitable length for crank (r2).