What is the value of cos(120)cos(30)+sin(120)sin(30) ?

The value of cos(120)cos(30)+sin(120)sin(30) is 0

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cos(120)cos(30)+sin(120)sin(30)

cos (12 0^{\circ}) cos (3 0^{\circ}) + sin (12 0^{\circ}) sin (3 0^{\circ})

0

Solution steps

cos (12 0^{\circ}) cos (3 0^{\circ}) + sin (12 0^{\circ}) sin (3 0^{\circ})

Use the following trivial identity:

cos (12 0^{\circ}) = - \frac{1}{2}

Use the following trivial identity:

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

Use the following trivial identity:

sin (12 0^{\circ}) = \frac{3}{2}

Use the following trivial identity:

sin (3 0^{\circ}) = \frac{1}{2}

= (- \frac{1}{2}) \frac{3}{2} + \frac{3}{2} \cdot \frac{1}{2}

Simplify

= 0

arctan (\frac{2}{- 2 3})

80 cos (6 0^{\circ})

arctan (\frac{9}{7})

4 cos (- \frac{π}{4})

sin (\frac{4 π}{7}) cos (\frac{5 π}{21}) - cos (\frac{4 π}{7}) sin (\frac{5 π}{21})

What is the value of cos(120)cos(30)+sin(120)sin(30) ?
The value of cos(120)cos(30)+sin(120)sin(30) is 0