What is the value of cos(105)cos(75) ?

The value of cos(105)cos(75) is (sqrt(3)-2)/4

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

Popular >

cos(105)cos(75)

cos (10 5^{\circ}) cos (7 5^{\circ})

\frac{3 - 2}{4}

Solution steps

cos (10 5^{\circ}) cos (7 5^{\circ})

Rewrite using trig identities:

\frac{cos ( 3 0 ^{\circ} ) + cos ( 18 0 ^{\circ} )}{2}

= \frac{cos ( 3 0 ^{\circ} ) + cos ( 18 0 ^{\circ} )}{2}

Use the following trivial identity:

cos (3 0^{\circ}) = \frac{3}{2}

Use the following trivial identity:

cos (18 0^{\circ}) = (- 1)

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

Simplify

\frac{\frac{3}{2} - 1}{2} : \frac{3 - 2}{4}

= \frac{3 - 2}{4}

arccos (\frac{35}{77})

sin (- \frac{15 π}{4})

e^{0} cos (\frac{π}{3})

cos (π \frac{1}{2})

sin^{6} (\frac{π}{2})

What is the value of cos(105)cos(75) ?
The value of cos(105)cos(75) is (sqrt(3)-2)/4