# Math Help - Maths M1 Mechanics RESOLVING FORCES

1. ## Maths M1 Mechanics RESOLVING FORCES

Please can someone help me on this question:

Two forces of magnitude 5N and 6N act on the point 0. The angle between the two forces is X

The resultant of the two forces has magnitude 5N.

Calculate the value of X.

Many thanks,
languages

2. Originally Posted by languages
Please can someone help me on this question:

Two forces of magnitude 5N and 6N act on the point 0. The angle between the two forces is X

The resultant of the two forces has magnitude 5N.

Calculate the value of X.

Many thanks,
languages
This is basic law of cosines: $c^2 = a^2 + b^2 - 2ab \cos C$

so you have

$5^2 = 5^2 + 6^2 - 2(5)(6) \cos C$

$0 = 36 - 60 \cos C$

$60 \cos C = 36$

$\cos C = \frac{36}{60}$

$\cos C = \frac{3}{5}$

3. Many thanks iceman fan!