Difference between a trig equation that is an identity and a trig equation that is not an identity

What is the difference between a trig equation that is an identity and a trig equation that is not an identity? Provide an example to clarify.

Trigonometry equation

s=4sin(t+^0) with a force acting upon it P=7sin(t-39) If E at time t is ps and E=-14cos(2t-60) How do you arrive at this.

Find all solutions to the given trigonometric equation.

Find all solutions of the equation Sec^2-2=0 The answer is A+B(k)(pi) where k is any integer and 0

Graphs of functions/ Size and Mass

A lobster boat is situated due west of a lighthouse. A barge is 12 km south of the lobster boat. From the barge the bearing to the lighthouse is 63 degrees (12 km is the length of the side adjacent to the 63 degree bearing). How far is the lobster boat from the light house? A recent land survey was conducted on a vacant lot where a commercial building is to be erected. The plans for the future building construction call for a building having a roof supported by two sets of beams. The beams in the front are 8 feet high and the back beams are 6.5 feet high. The distance between the front and back beams is 8 feet. At what angle will the roof lay on the front beam? Latitude presents spec... click for more

Trigonometry

What is the difference between a trig equation that is an identity and a trig equation that is not an identity? Provide an example to clarify.