is false in general; see the graphs. Now, I know you want to prove , but how can you deal with trigonometry if you don't know the order of arithmetic operations? The second equality is also false in general; see the graphs.
is false in general; see the graphs. Now, I know you want to prove , but how can you deal with trigonometry if you don't know the order of arithmetic operations? The second equality is also false in general; see the graphs.