Question

The force of gravity that the sun exerts on a planet is directed

Answer 1

the force of gravity is directed along the line between the center of the two masses. Newtons 3rd law states that every force has an equal and opposite reaction. So the force that the sun exerts on a planet is the same as the force that the planet exerts on the sun.

Answer 2

where is the tensile force directed in this diagram?

Tensile force in this diagram is similar to the force of gravity that sun exerts on a planet in sun-planet system.