Would it be two equilateral triangles?
I'm sorry if this doesn't help I don't really know what type of triangle that is.
1. We assume, that the number 432 is 100% - because it's the output value of the task.
<span>2. We assume, that x is the value we are looking for. </span>
<span>3. If 432 is 100%, so we can write it down as 432=100%. </span>
<span>4. We know, that x is 45% of the output value, so we can write it down as x=45%. </span>
5. Now we have two simple equations:
1) 432=100%
2) x=45%
where left sides of both of them have the same units, and both right sides have the same units, so we can do something like that:
432/x=100%/45%
6. Now we just have to solve the simple equation, and we will get the solution we are looking for.
7. Solution for what is 45% of 432
432/x=100/45
<span>(432/x)*x=(100/45)*x - </span>we multiply both sides of the equation by x
<span>432=2.22222222222*x - </span>we divide both sides of the equation by (2.22222222222) to get x
<span>432/2.22222222222=x </span>
<span>194.4=x </span>
x=194.4
<span>now we have: </span>
<span>45% of 432=194.4</span>
Answer: Hello mate!
Clairaut’s Theorem says that if you have a function f(x,y) that have defined and continuous second partial derivates in (ai, bj) ∈ A
for all the elements in A, the, for all the elements on A you get:

This says that is the same taking first a partial derivate with respect to x and then a partial derivate with respect to y, that taking first the partial derivate with respect to y and after that the one with respect to x.
Now our function is u(x,y) = tan (2x + 3y), and want to verify the theorem for this, so lets see the partial derivates of u. For the derivates you could use tables, for example, using that:


and now lets derivate this with respect to y.
using that 

Now if we first derivate by y, we get:

and now we derivate by x:

the mixed partial derivates are equal :)