Question

For a given triangle it is known that cos A =-0.5, where 0°

Based on the information given above, the value of angle(s) A in standard position
could be
A)60°
B)120°
C)210°
D)300°

Answer 1

120

Explanation:

Here, we want to get the possible value of A

Now, we should understand that the value of an angle in triangle cannot be more than 180

Also, cosine can only be negative in the second and the 3rd quadrant

So,

arc cos (-0.5) = 120 , 300 , 60

But 60 is not correct as it will give a negative value

300 is not correct also as it is more than the angles present in a triangle

Thus, our answer is 120