What is the value of -picos(-pi) ?

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Popular >

-picos(-pi)

- π cos (- π)

π

Decimal Notation

3.14159 \dots

Solution steps

- π cos (- π)

Rewrite using trig identities:

cos (- π) = - 1

cos (- π)

Use the following property:

cos (- x) = cos (x)

cos (- π) = cos (π)

= cos (π)

Use the following trivial identity:

cos (π) = (- 1)

cos (π)

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}

= (- 1)

= - 1

= - π (- 1)

Simplify

= π

65 cos (5 2^{\circ})

arctan (0.6666600000000 \dots)

2 sin (5)

- arctan (200)

arctan (\frac{2640 + 1980}{15000})