What is the value of cos(pi)+4 ?

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cos(pi)+4

cos (π) + 4

3

Solution steps

cos (π) + 4

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 + 4

Simplify

= 3

sin (- 10 0^{\circ})

arccos (\frac{2}{3.6})

arccos (\frac{1}{- 2})

\frac{sin ^{2} ( \frac{0}{2} )}{( \frac{0}{2} ) ^{2}}

cos^{2} (3 0^{\circ}) - sin^{2} (13 5^{\circ}) + 8 sin (4 5^{\circ}) cos (13 5^{\circ})