This is the concept of calculus, to get dy/dx we proceed as follows;
(cos πx+ sin πy)5=54
first we divide through by 5 we get:
(cos πx+ sin πy)=10.8
differentiating our expression we get:
-sin πx+y'cos πy=0
this can be written as:
y'cos πy=sin πx
dividing both sides by cos πy we get:
y'=[sin πx]/[cos πy]
The answer is y'=[sin πx]/[cos πy]
