Two sides of a triangle are $15cm$ and $20cm$ long respectively. How fast is the third side increasing if the angle between the given sidesis $60$ degrees and is increasing at therate of $2deg/sec$? I tried solving it using the phythagorean theorem but I wasn't able to use $60 degrees$ so I was thinking my answer is wrong.
[Math] Two sides of a triangle are 15cm and 20cm long respectively…
calculus
Best Answer
Hint: Use the cosine rule: $$a^2=b^2+c^2 -2bc \cos \theta$$ where $b$ and $c$ are fixed at 15 and 20, while the angle is changing but remember to convert from degrees to radians!