Answer: 48
Step-by-step explanation: COB and DOA are vertical angles. This means the two of them have the same measure. Because we know the measuremen of DOA, we can easily find the measuremen for COB since these angles are the same, so COB is 48 degrees.
From the chord theorem we know that:

so:

Answer C.
Refer to the diagram shown below. It shows a vertical cross-section of the paraboloid through its axis of symmetry.
Let the vertex of the parabola be at the origin. Then its equation is of the form
y = bx²
Because the parabola passes through (18,8), therefore
8 = b(18²)
b = 0.02469
The parabola is y = 0.02469x².
The receiver should be placed at the focal point of the paraboloid for optimal reception.
The y-coordinate of the focus is
a = 1/(4b) = 1/0.098765 = 10.125 in
Answer: The receiver is located at 10.125 inches from the vertex.
Answer:
<em>20 boys </em>
Step-by-step explanation:
b = 2g
100% - 20% = 80%
80% ÷ 2 = 40% = 0.4
0.4g = 4 ⇒ g = 4 ÷ 0.4 = 10
b = 2 × 10 = 20
There are 10girls and <em>20 boys</em> study in the class.