Earlier in Lesson 1, the method of resolving a vector into its components was thoroughly discussed. During that lesson, it was said that any vector that is directed at an angle to the customary coordinate axis can be considered to have two parts - each part being directed along one of the axes - either horizontally or vertically. The parts of the single vector are called components and describe the influence of that single vector in that given direction. One example that was given during Lesson 1 was the example of Fido being pulled upon by a dog chain. If the chain is pulled UPWARDS and to the right, then there is a tensional FORCE acting upwards and rightwards upon Fido. That single force can be resolved into two components - one directed upwards and the other directed rightwards. Each component describes the influence of that chain in the given direction. The vertical component describes the UPWARD influence of the force upon Fido and the horizontal component describes the rightward influence of the force upon Fido. DETERMINING the Components of a VectorThe task of determining the amount of influence of a single vector in a given direction involves the use of trigonometric functions. The use of these functions to determine the components of a single vector was also discussed in Lesson 1 of this unit. As a quick REVIEW, let's consider the use of SOH CAH TOA to determine the components of force acting upon Fido. Assume that the chain is exerting a 60 N force upon Fido at an angle of 40 degrees above the horizontal. A quick sketch of the situation reveals that to determine the vertical component of force, the sine function can be used and to determine the horizontal component of force, the cosine function can be used. The solution to this problem is shown below.