The number of board feet in a 16 foot long tree is approximated by the model f(d) = 0.77d^2 -- 1.32d -- 9.31 where f is the number of board feet and d is the diameter (in inches) of the log. what diameter tree will produce the minimum number of board feet?

Grace is standing 18 feet from a lighthouse and kelly is standing 10 feet from grace. the angle that grace looks up to see the top of the lighthouse is 45°. the angle that kelly looks up to see the top of the lighthouse is y°. find the height, h, of the lighthouse. find the angle, rounded to the nearest tenth of a degree, in which kelly looks up to the top of the lighthouse. to the nearest tenth of a degree, find the value of x° . in two or more sentences, explain your calculations