if a triangle has the sides a=412, b=324, c=636, what is the measure of angle A?

we can choose from these answers:

a) 119.1

b) 34.5

c) 48.7

d) 26.4

e) none of these

Printable View

- May 20th 2010, 11:58 AMstarrynightfinding the measure of an angle
if a triangle has the sides a=412, b=324, c=636, what is the measure of angle A?

we can choose from these answers:

a) 119.1

b) 34.5

c) 48.7

d) 26.4

e) none of these - May 20th 2010, 12:03 PMearboth
- May 20th 2010, 12:03 PMmasters
- May 20th 2010, 12:13 PMstarrynight
i get an answer of 145.5202602. is this correct?

- May 21st 2010, 02:24 AMearboth
Obviously not:

1. According to the Cosine rule an angle greater than 90° must be opposite the largest side in the triangle. That is the side c and not the side a, which is opposite the angle at A.

2. You probably have forgotten about the negative sign in the denominator and therefore the correct result would be:

180° - 145.5202602° = 34.479...°