Related rates and implicit differentiation

[blade123]

Homework Statement

A plane flying with a constant speed of 300 km/h passes over a ground radar station at an altitude of 1 km and climbs at an angle of 30 degrees. At what rate is the distance from the plane to the radar station increasing a minute later?

Homework Equations

a²+b²=c²

The Attempt at a Solution

I got to (y+1)²+x²=d₂²

It's that extra kilometer that's bothering me. It gives the answer as approx 296 km/h

d₁ is the distance between the starting and current point (5 km) and d₁' is 300 km/h

I don't know how to get from d₁ to d₂

 

[blade123]

Of course, right as I post it I figure it out.

x²+y²=d₁²

Sub in, differentiate, solve. I'm going to leave it up, just for anyone who wants to check it out. Silly me...