Foo - Trig Function Question

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.



PDA

View Full Version : Trig Function Question

Tom Stormcrowe
02-12-10, 07:01 PM
It's been years since I've worked any trig, and I was working an algebraic equation determining a distance between 2 points when the vectors are on a 90 degree tangent to each other from a common origin point (2 people walking, one at 2 mph and one at 4 mph). If it were a trig question, I'd have a known hypotenuse of 3 miles, and unknown values for a and b, other than b=2a.


I just plain can't remember beyond this point.

AEO
02-12-10, 07:06 PM
so we know hyp., which is 3 and b=2a

http://faculty.uoit.ca/kay/G10_AppWebPage/

Pythagorean theorem says: c^2=(a^2)+(b^2)
since b=2A and c=3, you can substitute it into the equation and write it as
9=(a^2)+(2a^2)
Tom Stormcrowe
02-12-10, 07:07 PM
AAAAH, Thanks! I knew I was on the right track. :p

So, then a=SQRT3 and b=2(SQRT3), then. I ignored the negative result since I was using it for distance in the real world, by the way.

couch_incident
02-12-10, 07:26 PM
Two parts couch, one part match. Sorry Tom, I killed my Trig brain cells years ago.

Couch
Tom Stormcrowe
02-12-10, 07:35 PM
no worries, couch. ;) Mine are very rusty. :p
graham hull
02-12-10, 07:47 PM
AAAAH, Thanks! I knew I was on the right track. :p

So, then a=SQRT3 and b=2(SQRT3), then. I ignored the negative result since I was using it for distance in the real world, by the way.

Tom, you didn't quite get there:=

9=a^2+(2a)^2
9=a^2+4a^2
9=5a^2
9/5=a^2
SQRT(9/5)=a

Enjoy
Tom Stormcrowe
02-12-10, 07:53 PM
Gah, OK, thanks. :p