## anonymous one year ago What is the value of x in the circle below

1. anonymous

2. mathstudent55

x is the radius of the circle, right?

3. anonymous

I think yes

4. mathstudent55

Yes, it is. Here is another radius. All radii are congruent. |dw:1438042883506:dw|

5. mathstudent55

can you find the upper x? |dw:1438042948351:dw|

6. anonymous

hmm i want to say 18?

7. mathstudent55

Notice we are dealing with a right triangle, and we can call upon our friend, Mr. Pythagoras, to help us.

8. anonymous

16^2 + 4^2 = x

9. mathstudent55

Use the Pythagorean theorem. x is the radius of the circle and is the hypotenuse of the triangle.

10. anonymous

Nice job at explaining @mathstudent55

11. mathstudent55

@omgitsjc Do you know how to use the Pythagorean theorem?

12. anonymous

no not really

13. mathstudent55

|dw:1438043205414:dw|

14. mathstudent55

In a right triangle, we call the two legs (the sides that form the right angle) legs a and b. The longest side, opposite the right angle, is the hypotenuse. We call the hypotenuse c.

15. mathstudent55

The Pythagorean theorem states that $$a^2 + b^2 = c^2$$ is true for every right triangle.

16. anonymous

is it 16.49?

17. mathstudent55

Look at the last picture above. We have a = 4; b = 16; we need c $$4^2 + 16 ^2 = c^2$$ $$c = \sqrt {272}$$ $$c \approx 16.49$$

18. mathstudent55

Correct.

19. mathstudent55

Remember to round off to the nearest tenth.

20. mathstudent55

@Nixy Thanks.

21. anonymous

Thank you!

22. mathstudent55

You're welcome.