2 questions on area between curves! help please!

Ahh, yikes. I just typed out all of the images to prevent any further mishaps hah.

Find c > 0 such that the area of the region enclosed by the parabolas

y = x^2 - c^2 and y = c^2 - x^2 is 30.

Find the area of the region bounded by the parabola y=4x^2, the tangent line to this parabola at (3,36) and the x axis.

Ok, so my method of solving the first one was kind of strange, and I'm fairly certain that I used a completely incorrect method, but here it is...

I assumed that if I found the area in two quadrants then I could just multiply it by 2 and get the total area. So I did y = x^2 - c^2 = area of 15. Then I integrated, plugged in -c and c for x and solved but I came up with a wrong answer, which I think was something like 2.83.

For the second problem I found the began by finding the derivative which was 8x then found the equation for the line by plugging in 36, 3, 8 into y=mx+b equation, which ended up being y=8x+12. Then I integrated

S 8x+12 - 4x^2 and I'm not sure what to even use as the limits at this point, but I made multiple guesses and was wrong on all of them.

HELP PLEASE!!