In `triangle ABC`, if a=3, b=4, and c=5, then find the value of cosA.

Explanation

To find the value of cosA in triangle ABC where a = 3, b = 4, and c = 5, we can follow these steps:

### Step 1: Verify if the triangle is a right triangle
We check if the triangle satisfies the Pythagorean theorem, which states that for a right triangle, the square of the hypotenuse (the longest side) is equal to the sum of the squares of the other two sides.

Here, we have:
- a = 3 (one side)
- b = 4 (another side)
...