The base of an isosceles triangle is 84 ft., and one of the other sides is 50 ft. What is the altitude? 7. ... the base, one side, and the altitude make a right triangle, of which 60 is the hypotenuse and 42 the base. The altitude is the ... What is the principal crop? 4. Explain the ... land to be watered. This land must lie at a lower level than the top of the dam, so that the water may be made to flow over it by gravity.