If i measure a hypotenuse and i get 11 and then i double check my work by doing the a squared + b squared = c squared method and i get 12 why would these two be different

One expression below in undefined, and the other expression has a well defined value. which expression is undefined and explain why it has no value. which expression is defined? what is the value of that expression and how do you know? what is a different expression using a trig inverse function that is also undefined?

Find the area of the triangle formed by the origin and the points of intersection of parabolas y=−3x^2+20 and y=x^2−16.

Macy spent $36 on jeans. this was $12 less than twice what she spent on a shirt. which equation to solve this, 12x=36 2x=36-12 2x-12=36 12-2x=36