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Popular Trigonometry >

cos(45)*20

Solution

cos (4 5^{\circ}) \cdot 20

Solution

102

+1

Decimal

14.14213 \dots

Solution steps

cos (4 5^{\circ}) \cdot 20

Use the following trivial identity:

cos (4 5^{\circ}) = \frac{2}{2}

cos (4 5^{\circ})

cos (x)

periodicity table with

36 0^{\circ} n

cycle:

x 0 3 0^{\circ} 4 5^{\circ} 6 0^{\circ} 9 0^{\circ} 12 0^{\circ} 13 5^{\circ} 15 0^{\circ} cos (x) 1 \frac{3}{2} \frac{2}{2} \frac{1}{2} 0 - \frac{1}{2} - \frac{2}{2} - \frac{3}{2} x 18 0^{\circ} 21 0^{\circ} 22 5^{\circ} 24 0^{\circ} 27 0^{\circ} 30 0^{\circ} 31 5^{\circ} 33 0^{\circ} 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}

= \frac{2}{2} \cdot 20

Simplify

\frac{2}{2} \cdot 20 : 102

\frac{2}{2} \cdot 20

Multiply fractions:

a \cdot \frac{b}{c} = \frac{a \cdot b}{c}

= \frac{2 \cdot 20}{2}

Divide the numbers:

\frac{20}{2} = 10

= 102

= 102

Popular Examples

cos((13pi)/(36))cos(pi/9)+sin((13pi)/(36))sin(pi/9)

Frequently Asked Questions (FAQ)

What is the value of cos(45)*20 ?
The value of cos(45)*20 is 10sqrt(2)