He bought 3 small notebooks (3*7=21) and 3 large notebooks (3*10=30)
21+30=51
Answer:
The approximate value of the area is 
Step-by-step explanation:
we know that
The area of the circle (landing pad) is equal to

we have

substitute

----> exact value of the area
Find the approximate value
assume 
------> approximate value of the area
Yes it can be in fractions and in decimals
Answer:
I think its 12.56
Step-by-step explanation:
Multiply 4 and 3.14(thats pi)
The X coordinate has to be 0