Student Problem 9: Unit R Concept 2

1. What is this about?

This is an example of Unit R Concept 2. It is about how to use the sum and difference formulas when given values (right triangles). First, it is important to draw the appropriate triangles in the correct quadrants. Next is to find the missing piece of the triangle. Be CAREFUL of the SIGNS (+/-)!!!!! Finally, the numbers need to plug into the sum and difference formulas. In this case, the formulas that require are sin(u+v) and tan(u-v).

2. What does the reader need to pay attention to?

The readers need to pay attention to the quadrants of the triangles. Left and down is negative, right and up is positive. The hyponuses will be positive. There are two triangles that lie in two different quadrants, III and I.Quadrant III has both x- and y- values negative whereas every trig. function in Quadrant I is positive. For solving tangent, the readers can multiply by common denominator and solve for it.