Plzz do correctly worth a lot of points

In triangle abc, the length of side ab is 12 cm, the length of side bc is 5 cm, and the length of side ca is 9 cm. find the measure of angle a using the law of cosines.

If g^-1(x) is the inverse of g (x) which statement must be true

What ia the sum if the first 7 terms of the geometric series