I need help stuck on this hard problem I just want to get it right

When turned about its axis of rotation, which shape could have created this three-dimensional object?

Sam claims that cos x =sin y if x and y are congruent angels. is sam correct ?

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?