Verify that cos squared A plus Sin squared A is equal to 1 if A is equal to 90 degrees

Nick and nora are married and have three children in college. they have an adjusted gross income of 47,400. if their standard deduction is 12,600 itemized deductions are 14,200 and they get an exemption of 4000 for each adult and each dependent what is their taxable income

If the sales price of a dvd is $20 and the markup is 34%, what is the cost of the dvd?

21 a stick 7 inches long is broken into two pieces, so that one piece is twice as long as the other one. how long are the two pieces?