When 2 tangents are joined to a circle, the tangents are of equal length so the triangle is isosceles. Then again it is possible for it to be equilateral.
Given:
ΔONP and ΔMNL.
To find:
The method and additional information that will prove ΔONP and ΔMNL similar by the AA similarity postulate?
Solution:
According to AA similarity postulate, two triangles are similar if their two corresponding angles are congruent.
In ΔONP and ΔMNL,
(Vertically opposite angles)
To prove ΔONP and ΔMNL similar by the AA similarity postulate, we need one more pair of corresponding congruent angles.
Using a rigid transformation, we can prove

Since two corresponding angles are congruent in ΔONP and ΔMNL, therefore,
(AA postulate)
Therefore, the correct option is A.
Here's link to the answer:
tinyurl.com/wpazsebu
The amount of balls in a given layer can be found by squaring the layer it is in
4 layers
top layer (1st) is 1
2nd is 4
3rd layer is 9
4th is 16
add them up
1+4+9+16=30
30 in that pyramid