Two Dimensional Motion

Motion can have two forces.  For example, the current of a river acting upon the direction of a boat or the cross winds that impact the direction of an airplane.  To understand the net impact of two forces on an object we have to use basic trigonometry.  We reviewed the basic types of triangles: Scalene, Isoceleses, Equalateral, Obtuse and Right.  We reviewed that the sum of the angles in a triangle is 180 degrees.  We reviewed the difference between Radians and Degrees.  There are two times Pi radians in a circle.  This is important to understand because we will be using TI83 & 84 calculators and also Excel to calculate Sine, Cosine and Tangent.  One has to check the Mode in the calculators to ensure you are using Degrees and not Radians.  In Excel you have to convert degrees to radians before performing the calculations.  I introduced the students to SAHCOHTOA, an anagram for the basic trigonometric equations.
     SAH sine = adjacent over hypotenuse
     COH cosine = opposite over hypotenuse
     TOA tangent = opposite over adjacent

For practice, we measured the height of the library roof.  Each student stood back from the library wall at least 6 to 10 meters.  Then we used a protractor to measure the angle from where the student was situated to the top of the roof.  We therefore had the angle and the adjacent side of a right triangle.  To determine the height of the roof, which is the height of the library wall and is the opposite side of the triangle, we used the tangent calculation.