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

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

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

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

\frac{3}{2}

Solution steps

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

arccos (- 0.92761)

6 sin (26 0^{\circ})

4 sin (5 0^{\circ})

3 sin (34 0^{\circ})

arctan (tan (- \frac{3 π}{4}))

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