Confusing question but I would get 0, as if you have 4cm, that squared = 16cm^2. Therefore if it were increasing anymore, then you would not be able to get a value of 16.
In this problem the big angle will be equal to two times the smaller angle so the correct expression is:

Now we can rewrite the equation so:
Get a better picture I’ll help then
Answer:
Area of the composite figure = 42 in²
Step-by-step explanation:
Composite area of the given figure = Area of the rectangle + Area of the right triangle
Area of the rectangle = Length × Width
= 6 × 5
= 30 in²
Area of the right triangle = 
= 
= 12 in²
Area of the composite figure = 30 + 12
= 42 in²
t + 7 = 21
---Subtract 7 from both sides
t + 7 - 7 = 21 - 7
t = 14
Hope this helps!! :)