Question

3.Two posts, one 8ft high and the other 12ft high, stand 15ft apart. They are to be stayed by wires attached to a single stake at ground level, the wires running to the tops of the posts. Where the stake should be placed, to use the least amount of wire?
1.At a given instant the legs of a right triangle are 8 in., and 6 in., respectively. The first leg decreases at 1 in/min and the second increases at 2 in/min. At what rate is the area increasing after 2 min.?
2.An arc light is 15 feet above a sidewalk. A man 6 feet tall walks away from the point under the light at the rate of 5ft/sec. How fast is his shadow lengthening when he is 20 feet away from the point under the light?
3.A man starts walking eastward at 5ft/sec from a point A. Ten minutes later a second man starts walking west at the rate of 5ft/sec from a point B, 3000ft north of A. How fast are they separating 10 minutes after the second man starts?