1. ## solving equation

Hi, I am a very elderly person, I have long forgotten my mathematics but i now find the need to solve a simple equation:
In any right angle triangle having sides a,b,c and angles A,B,C, I want to solve for "c".
in my example, a=3. I think c = a cos A but no matter how many times I enter this data , I can not get the answer which is c = 5.
Please lead me through the actual steps to solve this using an engineering calculator.

2. Originally Posted by wjt
Hi, I am a very elderly person, I have long forgotten my mathematics but i now find the need to solve a simple equation:
In any right angle triangle having sides a,b,c and angles A,B,C, I want to solve for "c".
in my example, a=3. I think c = a cos A but no matter how many times I enter this data , I can not get the answer which is c = 5.
Please lead me through the actual steps to solve this using an engineering calculator.
What side is the hypotenuese (longest side - opposite the right angle) in your triangle?

Chances are it will be some form of the Pythagorean Theorem:

$
c^2 = a^2+b^2$