A fishing pole makes an angle of 20 degrees with the horizontal. What is the torque exerted by the fish about an axis perpendicular to the page and passing through the fisher's hand

Depemds on the length of the fishing pole and the magnituide and direction of the force the fish exerts. In general torque can be calculated using \vec T = \vec F \times \vec R, which gives a magnitude for T of F times R times the sine of the angle between them.