Answer:"Haruto is correct because the angle is coterminal with 3pi/4 and the reference angle is pi/4." Step-by-step explanation:Coterminal angle:Coterminal Angles are angles who share the same initial side and terminal sides. Finding coterminal angles is as simple as adding or subtracting 360° or 2π to each angle, depending on whether the given angle is in degrees or radians.Finding if 3pi/4 is coterminal with 19pi/4:19pi/4= 16pi/4 + 3pi/4= 4pi + 3pi/4= 2(2pi) + 3pi/4= 2(360°) + 3pi/4= 3pi/4Hence they are coterminal.Reference angle:The smallest angle that the terminal side makes with x-axis.3pi/4 falls in second quadrant.In 2nd quadrant, reference angle is given as = pi - 3pi/4reference angle = pi/4.