Search results
Results from the WOW.Com Content Network
The values of sine and cosine of 30 and 60 degrees are derived by analysis of the equilateral triangle. In an equilateral triangle, the 3 angles are equal and sum to 180°, therefore each corner angle is 60°. Bisecting one corner, the special right triangle with angles 30-60-90 is obtained.
Subtracting from both sides and dividing by 2 by two yields the power-reduction formula for sine: = ( ()). The half-angle formula for sine can be obtained by replacing θ {\displaystyle \theta } with θ / 2 {\displaystyle \theta /2} and taking the square-root of both sides: sin ( θ / 2 ) = ± ( 1 − cos θ ) / 2 ...
sin(x) cos(x) Degrees Radians Gradians Turns Exact Decimal Exact Decimal 0° 0 0 g: 0 0 0 1 1 30° 1 / 6 π 33 + 1 / 3 g 1 / 12 1 / 2 0.5 0.8660 45° 1 / 4 π: 50 g 1 / 8 0.7071 0.7071 60° 1 / 3 π 66 + 2 / 3 g 1 / 6
The formulas for addition and subtraction involving a small angle may be used for interpolating between trigonometric table values: Example: sin(0.755) = (+) + () + () where the values for sin(0.75) and cos(0.75) are obtained from trigonometric table. The result is accurate to the four digits given.
Abu al-Wafa had sine tables in 0.25° increments, to 8 decimal places of accuracy, and accurate tables of tangent values. [16] He also made important innovations in spherical trigonometry [ 17 ] [ 18 ] [ 19 ] The Persian polymath Nasir al-Din al-Tusi has been described as the creator of trigonometry as a mathematical discipline in its own right.
Comparison of graphs of the parabolas x(180 − x)/8100 and x(180 − x)/9000 with the graph of sin x (with x in degrees) The part of the graph of sin x in the range from 0° to 180° "looks like" part of a parabola through the points (0, 0) and (180, 0). The general form of such a parabola is (). The parabola that also passes through (90, 1 ...
The angle between the horizontal line and the shown diagonal is 1 / 2 (a + b). This is a geometric way to prove the particular tangent half-angle formula that says tan 1 / 2 (a + b) = (sin a + sin b) / (cos a + cos b). The formulae sin 1 / 2 (a + b) and cos 1 / 2 (a + b) are the ratios of the actual distances to ...
Quadrant 1 (angles from 0 to 90 degrees, or 0 to π/2 radians): All trigonometric functions are positive in this quadrant. Quadrant 2 (angles from 90 to 180 degrees, or π/2 to π radians): Sine and cosecant functions are positive in this quadrant.