Answer: 
Step-by-step explanation:
By definition, an Isosceles triangle has two equal sides and its opposite angles are congruent.
Observe the figure attached, where the isosceles triangle is divided into two equal right triangles.
So, in this case you need to use the following Trigonometric Identity:

In this case, you can identify that:

Substituting values, and solving for "x", you get:

Therefore, the length of BC rounded to nearest tenth, is:

Make the equations equal and solve for x
- 2x²+6x+1=-4x²+1
- 6x²+6x=0
- 6x(x+1)=0
- 6x=0 or x+1=0
- x=0 or x=-1
For x=0
For x=-1
The solutions are
Graph attached
I only got 22-25 done cause its been a long time since ive done these so i don't remember how to do the first two ):
What does the rest of the question say??
17. 9
18. 12
19. 16
20. 56
21. 143
22. 14
23. 27
24. 7