helping granddaughter with math homework

[Lissa]

A funny thing happened when I was a senior in high school. I forgot to bring my calculator on the day of a physics test. Besides long division and multiplication, part of solving the problems was to take trig functions and punch them into your calculator. I didn't have my calculator. :ph34r: I worked the problems to the end with the trig functions still in the answer. Then, being way to smart for my own good when I was 18, I *estimated* the decimal equivalent of the trig functions in my head and put it behind one of those squiggly equals signs. :lol:I came close enough that when the science teacher handed back my graded test, he looked at me as if I had just beamed down from the Enterprise. Lot of good this stuff does me now that I work in shipping. :lol:

I just went about memorizing certain values. Like sin(pi/4) = cos(pi/4) = 0.7170, sin(pi/3) = cos(pi/6) = 0.8660, and sin(pi/6) = cos(pi/3) = .5 (then used the various mulitples of those around the circle by remembeingr what the sign of those trig functions were for each quadrant, so quad 1 = positive, quad 2 sin pos, cos neg, quad 3 both neg, quad 4 sin neg, cos pos). Then it just becomes a quick memorization of tan, cot, sec, and csc (sin/cos, cos/sin, 1/sin, and 1/cos) and doing that math quick in the head.