<h2><em><u>
Answer: 628.3</u></em></h2>
Step-by-step explanation: Tenth is always the first decimal point so 1 rounds down, making it 628.3.
ANSWER
The slant height is 40cm.
EXPLANATION
The lateral area of a cone is given by:

where r=10cm is the radius of the circle and l is the slant height.
It was also given that, the lateral area is 400π cm²
We substitute the values to get,

We now divide both sides by 10π.
This implies that,


Hence the slant height is 40cm.
Depends on what equation or question you want to be answered from the whole section of geometry...
the answer is 1 over 7225 if u want to know use cymath