Posted by sarah on Friday, June 28, 2013 at 10:39am.
Compute the area of a triangle with a base of 15 cm and an altitude of 10.5 in.
Area (to the nearest tenth) = cm2
I plugged everything into the area formula which is A = (1/2)bh .
A=.5x15x10.5= I got 78.75 rounded 78.8.
The computer keeps saying I am wrong. What am I doing wrong?

Math  Steve, Friday, June 28, 2013 at 10:45am
Looks good to me. Computer may have wrong answer. Better check with your instructor. Have you tried entering 78.7 just in case they rounded wrong?

Math  PsyDAG, Friday, June 28, 2013 at 10:50am
If your data are correct, I don't see anything you are doing wrong.

Math  Steve, Friday, June 28, 2013 at 10:55am
Aha! Note that the area is
(1/2)(15 cm)(10.5 in)
= (1/2)(15 cm)(26.67 cm)
= 200.0 cm^2
Gotta watch those units!
Not a trick question, but ...

Math  sarah, Friday, June 28, 2013 at 11:00am
How did you get 26.67?

Math  Steve, Friday, June 28, 2013 at 11:05am
you gotta know that
1 in = 2.54 cm

Math  sarah, Friday, June 28, 2013 at 11:07am
Omg Thank you !! I now know how to solve this type of problem the correct way ! Thank you so much !

Math  PsyDAG, Friday, June 28, 2013 at 11:07am
Sorry that I missed the difference in units.
10.5 inches = 26.67 cm.
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