What is the value of 2/(cos(45)) ?

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

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2/(cos(45))

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

22

Decimal Notation

2.82842 \dots

Solution steps

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

Simplify

\frac{2}{\frac{2}{2}} : 22

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

Apply the fraction rule:

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

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

Multiply the numbers:

2 \cdot 2 = 4

= \frac{4}{2}

Factor

4 : 2^{2}

Factor

4 = 2^{2}

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

Cancel

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

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

Apply radical rule:

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

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

Apply exponent rule:

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

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

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

Subtract the numbers:

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

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

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

2^{\frac{3}{2}} = 22

2^{\frac{3}{2}}

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

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

Apply exponent rule:

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

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

Refine

= 22

= 22

= 22

arccos (cos (- \frac{5 π}{6}))

sin (2 arcsin (- \frac{3}{5}))

1 sin (3 0^{\circ})

40 \cdot cos (3 0^{\circ})

39 (cos (\frac{π}{2}) + i sin (\frac{π}{2}))