Trigonometric Functions


There are six trigonometric functions: sine (sin), cosine (cos), tangent (tan), cotangent (cot), secant (sec) and cosecant (csc). The three major trigonometric functions (sin, cos, tan) each have their own keys. However, the three minor trigonometric functions must be calculated using their reciprocal definitions:

Warning . The notation sin-1(θ) represents the inverse sine function, not the reciprocal of the sine function.

When working with trigonometric functions, be sure the calculator is in the correct Angle mode for your application. From a given screen, press CTRL SETUP to access the mode menu. Highlight the Angle item. Then select press the function key to select the angle measure appropriate for your application.

When working with a triangle or a geographical positioning system, use degree mode unless otherwise directed. When working with a graph or analytic trigonometry (e.g., solving a trigonometric equation), use radian mode unless otherwise directed. Most calculator errors in trigonometry occur because the calculator is in the wrong mode.

To view the graph of a trigonometric function, enter the function in the equation editor. For example, press MENU 3 to access the equation editor and enter Y1 = sin(X). To view the graph, press F5 to select DRAW. After the graph is drawn, then press F2 to access the zoom menu, select B:QUICK from the zoom menu, press the right arrow on the thumb pad key to access the quick submenu, then press 2 to select 2:Trig. The graph is redrawn with the horizontal tic marks placed at intervals of π/2. Further, inappropriate vertical lines for asymptotes in the graph of the tangent function, are not drawn.

For convenience, press CTRL 0 to toggle off and on the graph menu at the bottom of the screen.