I think the first one or the thrid one
hope this help
Answer:

Step-by-step explanation:
<h3>to understand this</h3><h3>you need to know about:</h3>
<h3>tips and formulas:</h3>
<h3>let's solve:</h3>





18. S=r^2-t^2
S+t^2=r^2
r=sqrt(S+t^2)
20. Tan 18=x/12
x=12×Tan 18
x=3.899036355
x=3.90
I hope this helps.
Answer:
i cannot say that i am perfect or good in math but if there is any problem then i will try to solve.
Step-by-step explanation:
Given:
Consider the below figure attached with this equation.
Quadrilateral QRST is a parallelogram.
To find:
The value of x.
Solution:
We know that the sum of two consecutive interior angles of a parallelogram is 180 degrees because they are supplementary angles.
In parallelogram QRST,
On comparing both sides, we get
Divide both sides by 12.
Therefore, the value of x is 16.