Cos 15 degrees in radians is written as cos (15° × π/180°), i.e., cos (π/12) or cos (0.261799. . .). In this article, we will discuss the methods to find the value of cos 15 degrees with examples.

Split 15 15 into two angles where the values of the six trigonometric functions are known. cos(45−30) cos (45 - 30) Separate negation. cos(45−(30)) cos (45 - (30)) Apply the difference of angles identity cos(x−y) = cos(x)cos(y)+sin(x)sin(y) cos (x - y) = cos (x) cos (y) + sin (x) sin (y).

Use our cos (x) calculator to find the cosine of 15 degrees - cos (15 °) - or the cosine of any angle in degrees and in radians.

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From the trigonometric identities we know that $\cos 2\theta =2{{\cos }^{2}}\theta -1$, in this double angle formula if we put θ = 15° then we get cos15° in terms of cos30° hence we can find the value of cos15°.

The value of cos 15° is `underlinebb((sqrt(3) + 1)/(2sqrt(2))`. Explanation: cos 15° = cos(45° – 30°) = cos 45° cos 30° + sin 45° sin 30° = `1/sqrt(2) sqrt(3)/2 + 1/sqrt(2) 1/2` = `sqrt(3)/(2sqrt(2)) + 1/(2sqrt(2))` = `(sqrt(3) + 1)/(2sqrt(2))`

Feb 26, 2017 · The cos of 15 degrees is (√6+√2)/4, the same as cos of 15 degrees in radians. To obtain 15 degrees in radian multiply 15° by $\pi$ / 180° = 1/12 $\pi$. Cos 15degrees = cos (1/12 × $\pi)$.

What is the value of cos (15) ?

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