What is the value of (20)/(cos(45)) ?

The value of (20)/(cos(45)) is 20sqrt(2)

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(20)/(cos(45))

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

202

Decimal Notation

28.28427 \dots

Solution steps

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

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{20}{\frac{2}{2}}

Simplify

\frac{20}{\frac{2}{2}} : 202

\frac{20}{\frac{2}{2}}

Apply the fraction rule:

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

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

Multiply the numbers:

20 \cdot 2 = 40

= \frac{40}{2}

Factor

40 : 2^{3} \cdot 5

Factor

40 = 2^{3} \cdot 5

= \frac{2 ^{3} \cdot 5}{2}

Cancel

\frac{2 ^{3} \cdot 5}{2} : 5 \cdot 2^{\frac{5}{2}}

\frac{2 ^{3} \cdot 5}{2}

Apply radical rule:

2 = 2^{\frac{1}{2}}

= \frac{2 ^{3} \cdot 5}{2 ^{\frac{1}{2}}}

Apply exponent rule:

\frac{x ^{a}}{x ^{b}} = x^{a - b}

\frac{2 ^{3}}{2 ^{\frac{1}{2}}} = 2^{3 - \frac{1}{2}}

= 5 \cdot 2^{- \frac{1}{2} + 3}

Subtract the numbers:

3 - \frac{1}{2} = \frac{5}{2}

= 5 \cdot 2^{\frac{5}{2}}

= 5 \cdot 2^{\frac{5}{2}}

2^{\frac{5}{2}} = 2^{2} 2

2^{\frac{5}{2}}

2^{\frac{5}{2}} = 2^{2 + \frac{1}{2}}

= 2^{2 + \frac{1}{2}}

Apply exponent rule:

x^{a + b} = x^{a} x^{b}

= 2^{2} \cdot 2^{\frac{1}{2}}

Refine

= 2^{2} 2

= 5 \cdot 2^{2} 2

2^{2} = 4

= 5 \cdot 42

Multiply the numbers:

5 \cdot 4 = 20

= 202

= 202

4 cosh (0)

cos (\frac{1}{3} π) \cdot 13

50 sin (3 8^{\circ})

\frac{- 2 sin ( 1 2 ^{\circ} )}{1.17}

sec (arctan (\frac{3}{2}))