Please help! Pleaseee

Astick 2 m long is placed vertically at point b. the top of the stick is in line with the top of a tree as seen from point a, which is 3 m from the stick and 30 m from the tree. how tall is the tree?

Extra points! find the missing dimension! need asap

If t8 = 4 and t12 = −2, find the first three terms of the arithmetic sequence.