The angle OBC is 90 degrees, the equation is 18r = 144, r = 8 feet, and the length of the AB is 16 feet which is the length of the red sail in the logo.
What is a circle?
It is described as a set of points, where each point is at the same distance from a fixed point (called the center of a circle)
We have the figure shown in the picture with dimensions.
a) As we can see, the AOB is the diameter of the circle which is perpendicular to the CBD
So the angle ∠OBC will be a right angle.
∠OBC = 90 degree.
b) Length OE is the radius of the circle.
Let's suppose OE = r
Then in a right angle triangle OBC where ∠OBC = 90 degrees.
Applying Pythagoras theorem:
OC² = CB² + OB²
(CE + OE)² = CB² + OB²
CE = 9 ft, OE = r, CB = 15 feet, and OB = r (radius of the circle)
(9 + r)² = 15² + r²
81 + 18r + r² = 15² + r²
18r = 144
r = 8 feet
OE = r = 8 feet
c)
As the angle ∠OBC = 90 degrees, that's why the triangle OBC becomes a right angle triangle and OB⊥CB.
d)
In the circle, there is a red triangle, we can find one of the lengths of the triangle which is AB.
AB is the diameter of the circle
r = 8
Diameter AB = double the radius = 2(8) = 16 feet
AB = 16 feet
Thus, the angle OBC is 90 degrees, the equation is 18r = 144, r = 8 feet, and the length of the AB is 16 feet which is the length of the red sail in the logo.
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