Find the tangent plane to z 2 = x 3 + 2xy + y 3 at x, y = 1, 1.

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)

Which equation represents h for right triangle abc

The perimeter of ? cde is 55 cm. a rhombus dmfn is inscribed in this triangle so that vertices m, f, and n lie on the sides cd , ce , and de respectively. find cd and de if cf=8 cm and ef=12 cm. the answer is not cd=20 and de=15. i have tried that one, it does not work.