150 likes | 381 Views
ACT Trigonometry Review. 4 questions on the test. 2 will be quite easy. So lets start with a review of the basics. The easier trig questions will deal with the relationship between the sides of a right triangle. SOHCAHTOA. The sine of angle x = The cosine of angle x =
E N D
4 questions on the test • 2 will be quite easy. • So lets start with a review of the basics. • The easier trig questions will deal with the relationship between the sides of a right triangle.
SOHCAHTOA • The sine of angle x = • The cosine of angle x = • The tangent of angle x = hypotenuse opposite x adjacent
YOU’RE ALMOST DONE • Cosecant = • Secant = • Cotangent = 1/ tan
To make matters even better, a good calculator has buttons for sin, cos, and tan functions. Let’s try one • What is sin ө, if tan ө = 4/3? • (hint- draw a rt triangle) • So what about those sin-1, cos-1, and tan-1 buttons on my calculator? • And where do I find sec, csc, and cot?
2 important trig identities • sin2ө + cos2ө = 1 • Tan ө = • Simplify:
In the right triangle, sec ө is 25/7. What is sin ө? 3/25 5/25 7/25 24/45 25/7 ө
HARDER TRIGONOMETRY • When graphing a trig function there are 2 important coefficients, a and b. a sin(b ө) The 2 coefficients tell about the amplitude (how tall it is) and the period of the graph (how long it takes to get through a complete cycle). If there are no coefficients, then a and b = 1 and the graph is the same as you’d get when you graph it on your calculator.
Increases in A, increase the amplitude. • This means if A = 2, then the amplitude is doubled. If A = ½, then the amplitude is cut in half. Increases in B decrease the period of the graph. It’s an inverse relationship.
You have 3 things to check when looking at a graph: • Is it sin or cos? (sin goes thru origin, cos starts at (0,1) • Is the period changed? (1 normal cycle is 2л) • And is the amplitude changed? (sin & cos go from -1 to 1 on the y –axis.