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Popular >

cos(pi/5)

Solution

cos (\frac{π}{5})

Solution

\frac{5 + 1}{4}

+1

Solution steps

cos (\frac{π}{5})

Show that:

cos (\frac{π}{5}) - sin (\frac{π}{10}) = \frac{1}{2}

Show that:

cos (\frac{π}{5}) + sin (\frac{π}{10}) = \frac{5}{4}

Add the following equations

cos (\frac{π}{5}) + sin (\frac{π}{10}) = \frac{5}{2}

((cos (\frac{π}{5}) + sin (\frac{π}{10})) + (cos (\frac{π}{5}) - sin (\frac{π}{10}))) = (\frac{5}{2} + \frac{1}{2})

Refine

cos (\frac{π}{5}) = \frac{5 + 1}{4}

= \frac{5 + 1}{4}

Popular Examples

tan (- \frac{4 π}{3})

2sin^2(x)+3cos(x)-3=0

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sin((17pi)/(12))

sin (\frac{17 π}{12})

sin (x) = - 1

prove (cos(3x))/(cos(x))=1-4sin^2(x)prove

\frac{cos ( 3 x )}{cos ( x )} = 1 - 4 sin^{2} (x)

Frequently Asked Questions (FAQ)

What is the value of cos(pi/5) ?
The value of cos(pi/5) is (sqrt(5)+1)/4