What are two methods for solving a real-world problem that can be represented by an equation?

What basic trigonometric identity would you use to verify that csc x sec x cot x = csc^(2)x

Identify the initial amount a and the growth factor b in the exponential function. a(x)=680*4.3^x

The figure shows triangle def and line segment bc, which is parallel to ef: triangle def has a point b on side de and point c on side df. the line bc is parallel to the line ef. part a: is triangle def similar to triangle dbc? explain using what you know about triangle similarity. part b: which line segment on triangle dbc corresponds to line segment ef? explain your answer. part c: which angle on triangle dbc corresponds to angle f? explain your answer. asap