Find the exact value of Tan(Cos-1(7/x))

Ps:Use the unit circle

An engineer scale model shows a building that is 3 inches tall. if the scale is 1 inch = 600 feet, how tall is the actual building?

Milk and ice cream are mixed together for a recipe. the total volume of the mixture is 1 cup. if the milk contains 2% fat, the cream contains 18% fat ,and the mixture contains 6% fat ,how much cream is in the mixture

Judy garland electronics operate on a net-profile rate of 20% on its printer cables. if the markup is $8.95 and the overhead is $4.31,find the net profit and the selling price? use the net-profit rate formula to solve this problem.