Allie, Beth, and Cathy are having a 3 way tug of war. Allie is pulling with a force of 30N, Beth with 50N, and Cathy with 70N. If the system is in equilibrium, what is the angle between Allie's rope and Beth's rope.(adsbygoogle = window.adsbygoogle || []).push({});

I used the cosine law, and

[tex]cos\theta=\frac{{30}^2+{50}^2-{70}^2}{2\cdot 30\cdot 50}[/tex]

[tex]\theta = 120[/tex]

But the answer is 60, because 180-120=60. Why?

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# Homework Help: Angle between two ropes

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