$cos A + cos (120^{0} + A) + c o s (120^{0} - A) =$

1

No worries! We‘ve got your back. Try BYJU‘S free classes today!

- 1

No worries! We‘ve got your back. Try BYJU‘S free classes today!

0

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

2

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is D $0$
$c o s A + cos (120^{0} + A) + cos (120^{0} - A)$
$= c o s A + 2 cos (\frac{120^{0} + A + 120^{0} - A}{2}) . cos (\frac{120^{0} + A - 120^{0} + A}{2})$
$= c o s A + 2 cos 120^{0} . c o s A$
$= c o s A + 2 \times (\frac{- 1}{2}) c o s A$
$= c o s A - c o s A$
$= 0$

Suggest Corrections

Similar questions

{sin}^{2} θ + {sin}^{2} (θ + 60^{0}) + {sin}^{2} (θ - 60^{0}) = \frac{3}{2}

cos α + cos (120^{0} + α) + cos (120^{0} - α) = 0

sin 750^{0} . cos 480^{0} + cos 120^{0} . cos 60^{0} = \frac{\sqrt{3} - 1}{4}

x cos θ = y cos (120^{0} + θ) = z cos (θ + 240^{0})

x y + y z + x z = 0

cos α + cos (120^{0} + α) + cos (120^{0} - α) = 0

\frac{cos A}{1 - tan A} + \frac{sin A}{1 - cot A} - sin A - cos A = 0

\frac{cos A - sin A + 1}{cos A + sin A - 1} = csc A + cot A

{csc}^{2} A = 1 + {cot}^{2} A

Join BYJU'S Learning Program