trigonometry is a field of mathematics that studies the relationships that exist between the sides of a triangle and its angles. How much do you know about the properties of triangles? Have you worked with them much in the past? These relationships and properties can be used to model many physical properties in the real world. One of these properties is called periodic motion, such as the motion made by a yo-yo going up and down. What kinds of periodic motion are you familiar with? Why might scientists and businesses be interested in tracking this type of motion using equations?

Some periodic motions, also known as armonic motions, with which much of us are familiar with are:

- The motion of the swinger when a kid is balancing forward and backward

- The motion of a pendulum

- The motion of the needles of a watch.

- The motion of a satelite around a planet.

- The spinning of the wheel of a stationary bycicle.

- A rocking chair

All the motions in which the object passes once and other times through the same point are periodic motions.

Both scientists and businesses are interested in tracking periodic motions using equations because they appear in many situations in nature and in daily life. The cycles are examples of periodic motion. By tracking this type of motion you can make models that permit you to explain the phenomena and predict cycles. This is predict facts that repeast with a certain period.