Math 251 - Section 14.4 - Tangent Plane & Linear Approximation (2 of 2)

Section 14.4 - Tangent Plane & Linear Approximation (2 of 2):
In this video we discussion differentiability of a multi-variable function, and introduce the differential and how to calculate with it. We cover an example where the differential is used to estimate the error in a calculated quantity.

[brendanspinelli]

24:26 Sorry, why does L(29pi/60, pi/50) = f(pi/2, 0) + fz(pi/2, 0)(x-pi/2) + fy(pi/2, 0)(y-0) ?
I dont get why we plug in (pi/2, 0) into the function for L(29pi/60, pi/50), shouldnt we plug in (29pi/60, pi/50) ?