LaaLa
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- Dec 21, 2018
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A satellite dish attached to a house receives the signal for television channels.
The dish is 48 centimetres long and 3 centimetres deep at the centre point. Its cross-section is in the shape of a parabola. The signal is received by the LNB, called the low noise block, which receives the television signal and filters out any interfering radio frequency. The LNB is attached to the feedhorn and is placed at the focal point of the parabola.
EXERCISE ONE: Find an equation that models the shape of the satellite dish and find the distance of the LNB from the centre of the dish.
ANSWER: The standard equation for a parabola is y2 = 4ax. The point (3, 24) is on the parabola. By substitution:
242 = 4 × a × 3
a = 48 The model is y2 = 192x. The focus is at (0, 48). The distance from the centre of the satellite dish to the focus is 48 centimetres.......
Thanks for taking the time to read and help me. I only have one question on this exercise...
When the answer is given here..(242 = 4 × a × 3) Where did the number 242 come from? How was it calculated?
I have tried every method of finding a way to get this number but it is no use.. I really suck! lol.
May I please have some assistance? Thank you
Note: I have gone back to all the papers of my study and it does not indicate this particular answer. Usually it only says y2 = 4 x a x 3 NOT 242 = 4 x a x 3! I know it may not be important to the actual answer but I am curious.
The dish is 48 centimetres long and 3 centimetres deep at the centre point. Its cross-section is in the shape of a parabola. The signal is received by the LNB, called the low noise block, which receives the television signal and filters out any interfering radio frequency. The LNB is attached to the feedhorn and is placed at the focal point of the parabola.
EXERCISE ONE: Find an equation that models the shape of the satellite dish and find the distance of the LNB from the centre of the dish.
ANSWER: The standard equation for a parabola is y2 = 4ax. The point (3, 24) is on the parabola. By substitution:
242 = 4 × a × 3
a = 48 The model is y2 = 192x. The focus is at (0, 48). The distance from the centre of the satellite dish to the focus is 48 centimetres.......
Thanks for taking the time to read and help me. I only have one question on this exercise...
When the answer is given here..(242 = 4 × a × 3) Where did the number 242 come from? How was it calculated?
I have tried every method of finding a way to get this number but it is no use.. I really suck! lol.
May I please have some assistance? Thank you
Note: I have gone back to all the papers of my study and it does not indicate this particular answer. Usually it only says y2 = 4 x a x 3 NOT 242 = 4 x a x 3! I know it may not be important to the actual answer but I am curious.
