Answer:
13
Step-by-step explanation:
there is a rule that says that if you add any 2 sides, it should be more than the third. 9+21 is greater than 13. 21+13 is greater than 9. 13 is the only number which if you add 9 to it it will be greater than 21. 12 will equal 21, but it still wont work.
hope this helps :))
It's not possible nothing but 1 times 5 is the only thing that multiplies to 5 and 1+5 doesn't equal 4
Answer:
7z
Step-by-step explanation:
subtracting a negative is like adding

Answer:
On the right is a circle with centre (0, 0), radius r and (x, y) any point on the circle. Distance between (0,0) and (x, y) equals the radius, r. If the centre is (0, 0), the equation of the circle will be of the form x2 + y2 = r2.