3. Find a third proportional to 4 and 7; 5 and 10;
and
4. Find a fourth proportional to 2, 5, and 4; 35, 20, and 14.
5. Write out the proofs for the following, stating the theorem in full in each case:
(a) The product of the extremes equals etc.
(b) If the product of two numbers equals the product of two other numbers, either pair etc.
(c) Alternation.