If sine theta is 0.28, then theta is 16.26 degrees. Cosine 2 theta, then, is 0.8432
It is 1.
For such simplifications, it is usually convenient to convert any trigonometric function that is not sine or cosine, into sine or cosine. In this case, you have: sin theta / sec theta = sin theta / (1/cos theta) = sin theta cos theta.
Tangent (theta) is defined as sine (theta) divided by cosine (theta). In a right triangle, it is also defined as opposite (Y) divided by adjacent (X).
The properties of the cosine and sine function are based on the X and Y coordinates of a point on a circle that has a radius of 1 and a center at the origin (X=0,Y=0). If the angle of the line from the origin to the edge of the circle, at any arbitrary point (X,Y), with respect to the X axis is theta, then sine(theta) is X, and cosine(theta) is Y.
Cosine squared theta = 1 + Sine squared theta
If sine theta is 0.28, then theta is 16.26 degrees. Cosine 2 theta, then, is 0.8432
Since secant theta is the same as 1 / cosine theta, the answer is any values for which cosine theta is zero, for example, pi/2.
It is 1.
cosine (90- theta) = sine (theta)
For such simplifications, it is usually convenient to convert any trigonometric function that is not sine or cosine, into sine or cosine. In this case, you have: sin theta / sec theta = sin theta / (1/cos theta) = sin theta cos theta.
It is cotangent(theta).
The cosine of theta is adjacent over hypotenuse, given a right triangle, theta not being the 90 degree angle, adjacent not being the hypotenuse, and theta being the angle between adjacent and hypotenuse. In a unit triangle, i.e. in a unit circle circumscribed with radius one, and theta and the center of the circle at the origin, cosine of theta is X.
If X and Y are sides of a right triangle, R is the hypoteneuse, and theta is the angle at the X-R vertex, then sin(theta) is Y / R and cosine(theta) is X / R. It follows, then, that X is R cosine(theta) and Y is R sin(theta)
To determine what negative sine squared plus cosine squared is equal to, start with the primary trigonometric identity, which is based on the pythagorean theorem...sin2(theta) + cos2(theta) = 1... and then solve for the question...cos2(theta) = 1 - sin2(theta)2 cos2(theta) = 1 - sin2(theta) + cos2(theta)2 cos2(theta) - 1 = - sin2(theta) + cos2(theta)
There is no easy simplification.
An even function is one where f(x) = f(-x) For cosine, cos(x) = cos(-x), thus cosine is an even function.