Technical point: standard notation for this would be . Don't use " " with differentials. More importantly, since there is an "h" rather than "a" in the formula, it should be

No, da= 0.1. Where did the "4" come from?

sub b=8.0m

sub h=6

db also equals .1

Does this make sense to you? Errors of .1 m in the measurement of the sides will cause an error of 7 square meters in the area? The calculated error would be (1/2)(6)(8)= 24 square meters. 7 square meters would be almost 1/3 of that!

P.S

square meters.

Note that is U= x+ y then dU= dx+ dy.

If A= xy then dA= ydx+ xdy. Dividing both sides by A= xy, .

Those give the old engineers "rule of thumb":

"When measurements are added, their errors add. When meaurements are multiplied, theirrelativeerrors add."

Here the relative error in height is and the relative error in base is . The relative error in the area is . Since the calculated area is (1/2)(.6)(.8)= .24, the maximum error is [tex]\frac{7}{24}(.24)= 0.7 square meters.