No you can't "just do it on the computer" to solve a real geometry or any other maths problem, unless you understand what it is you are trying to solve! The instrument is only a number-mill; and I am not sure what sort of geometry a computer can handle beyond just quoting definitions.
One of my nephews once told me something similar about maths generally. "You only need a calculator", he reckoned. A scientific calculator, maybe, but only a calculator.
"All right." I answered, "How do you decide what you are going to ask it?"
He couldn't answer that.
Just as well plenty of others like mathematics and find it lot easier than I do.
If not, we'd have no Internet on which to complain about maths.
We'd not even have electricity - whose calculations can include Trigonometry and Complex Numbers.