Locus Help. (1 Viewer)

[redpint]

Hello everyone. How do you do this question? A parabolic satellite dish has a diameter of 4m at a depth of 0.4m. Find the depth at which its diameter is 3.5m, correct to 1 decimal place.
Thanks!

 

[Bozza555]

is the answer 0.3m?

 

[redpint]

Yeah, how did you get that answer?

 

[Bozza555]

draw a parabola positioned on the origin, the parabola passes through the point (2,0.4) because at 0.4m high the radius is 2. Then i just let the parabolas equation be x^2=4ay, subbed in the point (2,0.4) to find a (a=2.5) then we want to find what y is when x=1.75 (half the diameter) so just sub that x point into the new equation and solve
let me know if you dont get it aha

 

[redpint]

I get it. Thank you!