Given: A right-angled triangle with AB=30 units, BC=40 units, and AC=50 units.
Required: To find the trigonometric ratio cos(A).
Explanation: The trigonometric ratio cosine is defined as the ratio of the adjacent side to the triangle's hypotenuse.

Here, in triangle ABC, the adjacent side for angle BAC is AB, and AC is the triangle's hypotenuse.
Hence

Final Answer:
