Those that bragged about being good at math...

sxyhrdrssr

I took my math praxis today ( I passed), but there was one question I was having a brain fart on and it's still bugging me...I need to know the answer! Here's the question: draw a rectangle with the width labeled 9 cm and length 12 cm. Begin on the bottom left corner labeling it A, the top left B, the top right C, and the bottom right D. What is the length between A and C? Can you explain how you got the answer. Thanks so much!

steel tiger

a^2+b^2=c^2 with a =width=9 and b=length=12 c=length of A to C

 

edit: it's the Pythagorean theorem 

Lindsay2907

It would form a triangle. So you're just figuring out the length of the 3rd side.  Isn't that formula something like A(squared) + B(squared)=C(squared)  ???

Lindsay2907

steel tiger:

a^2+b^2=c^2 with a =width=9 and b=length=12 c=length of A to C

SO:  81+144=225.   Square root of 225=15=length from A to C. 

barnwife

By length between A and C, are you referring to the diagonal of the rectangle? If so, you solve it by using "a squared plus b squared equals c squared?" In which case you square 12 and 9 (the length and width) and add them together. So 144 plus 81 equals 225 cm.  Then you take the square root of that which is 15 cm for that length. (Or you could just know that it's a 3, 4, 5 triangle. Which makes it lots easier.)

Someone please correct me if I am wrong!

sxyhrdrssr

Duh!!! Thanks so much! It's been a couple years since I was a student. I remember that formula and apparently selected the correct answer. Thanks so much ladies! You really are great at math:)

steel tiger

Lindsay2907:

steel tiger:

a^2+b^2=c^2 with a =width=9 and b=length=12 c=length of A to C

SO:  81+144=225.   Square root of 225=15=length from A to C. 

 

yes to the 15.