Help With Math HW???

Question

Show that the expression below is 0 when CosØ=r^4/R^4

r^4Csc²-R^4(CscØ)(CotØ)

please show how you got the answer

Answer 1

ok, well first of all, cscØ = 1/sinØ
cotØ = 1/tanØ = cosØ/sinØ
cosØ = r^4/R^4

Do all the replacements:
(r^4)/sin²Ø - R^4 * 1/sinØ * r^4/R^4 * 1/sinØ

In the term on the right, the R^4 cancels out of the top and bottom to leave you
(r^4)/sin²Ø - r^4/sin²Ø

And that's 0.