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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