I am sorry i have no idea. :( But i can ask my brother who is in a higher grade than i. i will ask him when he gets home for you. :)
Given:
CH = 3960 miles
Altitude = 240 miles
To find:
The distance from the space station to the horizon.
Solution:
The reference image for answer is attached below.
Radius = 3960 miles
CD = CH = 3960
ED = 240
EC = CD + ED
= 3960 + 240
EC = 4200 miles
By Pythagorean theorem:



Subtract 15681600 from both sides.


Taking square root on both sides, we get


The distance from space station to the horizon is approximately 1400 miles.
Sqrt(21x+1) = x+5
21x + 1 = x^2 + 10x + 25
x^2 - 11x + 24 = 0
(x-3)(x-8) = 0
x = 3 or x = 8
Here, Area of Square = a²
Area of parallelogram = a * b
Area of Trapezoid = (a+b)/2 * h
Area of Triangle = bh/2
In question, it says "half of the base" not bases, so most appropriate answer would be: Option D) Triangle
Hope this helps!
The half angle formula is:
sin x/2 = +/- √ (( 1-cos x ) / 2 )
5π/12 = 5π/6 : 2
sin 5π/12 = +/- √(( 1 - cos ( 5π/6)) / 2 )
cos 5π/6 = cos 150° = -√3/2
≈ 0.966 ( this is sin 5π/12 )