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cos(30)cos(55)+sin(30)sin(55)=cos(30-55) = cos(-25)=cos(25)

Note: cos(a)=cos(-a) for any angle 'a'.

cos(a)cos(b)+sin(a)sin(b)=cos(a-b) for any 'a' and 'b'.

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Comsoon

Q: What is this expression as the cosine of an angle cos30cos55 plus sin30sin55?

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Fora right angle triangle: cosine angle = adjacent/hypotenuse

Cosine is 0.5

cosine = adjacent/hypotenuse

As a decimal: 0.866 As a fraction: √(3)/2

If you know the angle's sine, cosine, or tangent, enter it into the calculator and press <inverse> sine, cosine, or tangent. On MS Calc, in Scientific Mode, using Degrees, enter 0.5, then check Inv and the press sin. You should get 30 degrees. The other functions work similarly.

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Fora right angle triangle: cosine angle = adjacent/hypotenuse

Cosine is 0.5

The cosine function is mathematical equation to determine the adjacent angle of a triangle. The cosine of an angle is the ratio of the length of the hypotenuse: so called because it is the sine of the co-angle.

In a right triangle, the cosine of an angle is defined as the ratio of the adjacent side of that angle to the hypotenuse.

You mean, you have the cosine, and want the angle? That is called arc-cosine, often written as cos-1x. Your scientific calculator should have a "shift" key or something similar, which you press, followed by the cosine key. That will give you the inverse cosine or arc-cosine.

In a right angle triangle it is: cosine ratio = adjacent/hypotenuse

cosine(59 degrees) = 0.51504 (rounded)

Sine of the angle to its cosine.

Sine and the cosine of the angle.

The secant of an angle is the reciprocal of the cosine of the angle. So the secant is not defined whenever the cosine is zero That is, whenever the angle is a multiple of 180 degrees (or pi radians).

at a 45 degree angle, or pi/4

The cosine is Â±1/sqrt(5) = Â±0.4472 (approx).