What is the value of cos((7pi)/(12))+cos(pi/(12)) ?

The value of cos((7pi)/(12))+cos(pi/(12)) is (sqrt(2))/2

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Popular >

cos((7pi)/(12))+cos(pi/(12))

Solution

cos (\frac{7 π}{12}) + cos (\frac{π}{12})

Solution

\frac{2}{2}

Decimal Notation

0.70710 \dots

Solution steps

cos (\frac{7 π}{12}) + cos (\frac{π}{12})

Rewrite using trig identities:

2 cos (\frac{π}{3}) cos (\frac{π}{4})

cos (\frac{7 π}{12}) + cos (\frac{π}{12})

Use the Sum to Product identity:

cos (s) + cos (t) = 2 cos (\frac{s + t}{2}) cos (\frac{s - t}{2})

= 2 cos (\frac{\frac{7 π}{12} + \frac{π}{12}}{2}) cos (\frac{\frac{7 π}{12} - \frac{π}{12}}{2})

Simplify:

\frac{\frac{7 π}{12} + \frac{π}{12}}{2} = \frac{π}{3}

\frac{\frac{7 π}{12} + \frac{π}{12}}{2}

Combine the fractions

\frac{7 π}{12} + \frac{π}{12} : \frac{2 π}{3}

Apply rule

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

= \frac{7 π + π}{12}

Add similar elements:

7 π + π = 8 π

= \frac{8 π}{12}

Cancel the common factor:

4

= \frac{2 π}{3}

= \frac{\frac{2 π}{3}}{2}

Apply the fraction rule:

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

= \frac{2 π}{3 \cdot 2}

Multiply the numbers:

3 \cdot 2 = 6

= \frac{2 π}{6}

Cancel the common factor:

2

= \frac{π}{3}

Simplify:

\frac{\frac{7 π}{12} - \frac{π}{12}}{2} = \frac{π}{4}

\frac{\frac{7 π}{12} - \frac{π}{12}}{2}

Combine the fractions

\frac{7 π}{12} - \frac{π}{12} : \frac{π}{2}

Apply rule

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

= \frac{7 π - π}{12}

Add similar elements:

7 π - π = 6 π

= \frac{6 π}{12}

Cancel the common factor:

6

= \frac{π}{2}

= \frac{\frac{π}{2}}{2}

Apply the fraction rule:

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

= \frac{π}{2 \cdot 2}

Multiply the numbers:

2 \cdot 2 = 4

= \frac{π}{4}

= 2 cos (\frac{π}{3}) cos (\frac{π}{4})

= 2 cos (\frac{π}{3}) cos (\frac{π}{4})

Use the following trivial identity:

cos (\frac{π}{3}) = \frac{1}{2}

cos (\frac{π}{3})

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}

= \frac{1}{2}

Use the following trivial identity:

cos (\frac{π}{4}) = \frac{2}{2}

cos (\frac{π}{4})

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}

= \frac{2}{2}

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

Simplify

2 \cdot \frac{1}{2} \cdot \frac{2}{2} : \frac{2}{2}

2 \cdot \frac{1}{2} \cdot \frac{2}{2}

Multiply fractions:

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

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

Cancel the common factor:

2

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

Multiply:

1 \cdot 2 = 2

= \frac{2}{2}

= \frac{2}{2}

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Frequently Asked Questions (FAQ)

What is the value of cos((7pi)/(12))+cos(pi/(12)) ?
The value of cos((7pi)/(12))+cos(pi/(12)) is (sqrt(2))/2