The diameter of a tree was 10 in. During the following year, the circumference increased 2 in. About how much did the tree’s diameter increase? The tree’s cross-section area?
we are using linearization to predict the increase as you can see in the question but I couldn't figure out what to do
Use the formula $$A=\pi R^2$$ and $$C=2\pi R = \pi D$$ to get
$$dC=\pi dD$$ and $$dA=2\pi R dR$$
You know the values of $dC$ and $R$ so you can find $dD$ and $dA$