What is the value of cos(20)cos(10)-sin(20)sin(10) ?

The value of cos(20)cos(10)-sin(20)sin(10) is (sqrt(3))/2

English

Español

Português

Français

Deutsch

Italiano

Русский

中文(简体)

한국어

日本語

Tiếng Việt

עברית

العربية

Popular >

cos(20)cos(10)-sin(20)sin(10)

cos (2 0^{\circ}) cos (1 0^{\circ}) - sin (2 0^{\circ}) sin (1 0^{\circ})

\frac{3}{2}

Solution steps

cos (2 0^{\circ}) cos (1 0^{\circ}) - sin (2 0^{\circ}) sin (1 0^{\circ})

Rewrite using trig identities:

cos (3 0^{\circ})

= cos (3 0^{\circ})

Use the following trivial identity:

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

= \frac{3}{2}

cos (2 5^{\circ}) cos (1 5^{\circ}) - sin (2 5^{\circ}) sin (1 5^{\circ})

1 + sec^{2} (π)

arcsin (\frac{4}{11})

tan^{2} (- \frac{π}{4}) - 1

tan (\frac{9 π}{6})

What is the value of cos(20)cos(10)-sin(20)sin(10) ?
The value of cos(20)cos(10)-sin(20)sin(10) is (sqrt(3))/2