When you create a hip roof in a timber frame, there are different types of rafters used. The hip rafters (in purple) form the roofline and extend from the plate to the ridge. The jack rafters (in turquoise) connect from the plate (in red) to the hip rafter and are of different lengths, depending on where on the slope they are placed.
Since the jack rafters are at an angle to the hip rafter, some compound cutting is required to create their housing into the hip rafter. The jack rafters are also notched to sit securely on the plate. Structural screws are brought into play to secure the whole assembly together. The screws are drilled into the jack rafters from above and secure the jack rafters to both plate and hip rafter.