CRAZY Trigonometry Practice Question | A Level Maths

[@gayathrikumar5643]

Why cant A also be -1 since it's modulus

[@greenpenguin3154]

Can’t have negative ln

[@Ahmad-hr6zj]

We can look back at what our A actually is to see that A=-1 is not a solution.
So after we integrate both sides of the sec(x) sec(y) he instantly goes to an A inside the ln. He has missed some steps which are useful.
After we integrate both sides we are actually left with a +c we can put on the RHS of the equation.
Now we want to move this c inside the ln somehow to get our A. We can do this be deducing that ln(e^c) = c as ln is the inverse of e^x
Now our c is in ln form so now we can use log laws of addition to see we multiply the inside of our RHS term by e^c.
This e^c can be rewritten as A as it is just another constant. Now we can see that A=e^c and e^c is never negative so A=-1 cannot be a solution

[@NeilDoesMaths]

In terms of the modulus it doesn't make a difference had I taken A=-1 to be fair, but it would get set to be positive anyway, it wouldn't affect the solution sets. It's got nothing to do with what Ahmad said below lol, I can confirm I've not missed out any steps 😂

[@Faheemiqbal-t4i]

1st

[@raisulislam1608]

Ok but who asked?

[@Faheemiqbal-t4i]

@@raisulislam1608 😵