What is expand cos((3pi)/4) ?

The solution to expand cos((3pi)/4) is -(sqrt(2))/2

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expand cos((3pi)/4)

expand

cos (\frac{3 π}{4})

- \frac{2}{2}

Decimal

- 0.70710 \dots

Solution steps

cos (\frac{3 π}{4})

Use the following trivial identity:

cos (\frac{3 π}{4}) = - \frac{2}{2}

cos (x)

periodicity table with

2 πn

cycle:

x 0 \frac{π}{6} \frac{π}{4} \frac{π}{3} \frac{π}{2} \frac{2 π}{3} \frac{3 π}{4} \frac{5 π}{6} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x π \frac{7 π}{6} \frac{5 π}{4} \frac{4 π}{3} \frac{3 π}{2} \frac{5 π}{3} \frac{7 π}{4} \frac{11 π}{6} cos (x) - 1 - \frac{3}{2} - \frac{2}{2} - \frac{1}{2} 0 \frac{1}{2} \frac{2}{2} \frac{3}{2}

= - \frac{2}{2}

9 sin (5 (t - c))

(x + 1) e (x^{2} + 2 x)

4 (0.14 x + 2 = 11 x + 1)

\frac{( x - 5 ) ( x ^{2} - 25 )}{x}

(- 7 x^{2} + 4 x - 5) - (Q (x) = 2 x - 7)

What is expand cos((3pi)/4) ?
The solution to expand cos((3pi)/4) is -(sqrt(2))/2