4dm its altitude,and its area is 16dm2. Find the length of the base and altitude
What is the shape?
And, you already told us the altitude, so why ask for it?
This is an example of why some questions go unanswered.
The missing information makes it impossible to answer the question.
Before you hit that Submit button, make sure you have not left anything out, or repeated it unnecessarily.
Proofread your dang question!