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Mathematics 12 Online
OpenStudy (anonymous):

Need Geometry Help!

OpenStudy (anonymous):

jimthompson5910 (jim_thompson5910):

|dw:1405731225654:dw|

OpenStudy (anonymous):

@jim_thompson5910 has you covered.

jimthompson5910 (jim_thompson5910):

Use the pythagorean theorem \[\Large a^2 + b^2 = c^2\]

jimthompson5910 (jim_thompson5910):

In this case, a = unknown (we're solving for it) b = GH = 18 c = FH = 21 \[\Large a^2 + b^2 = c^2\] \[\Large a^2 + 18^2 = 21^2\] \[\Large a = ???\]

OpenStudy (anonymous):

Sorry just got these! one second!

OpenStudy (anonymous):

117?

jimthompson5910 (jim_thompson5910):

how are you getting that

OpenStudy (anonymous):

21x21=441-18x18=324=117

jimthompson5910 (jim_thompson5910):

\[\Large a^2 + b^2 = c^2\] \[\Large a^2 + 18^2 = 21^2\] \[\Large a^2 + 324 = 441\] \[\Large a^2 = 441 - 324\] \[\Large a^2 = 117\] \[\Large a = ???\]

OpenStudy (anonymous):

13689

jimthompson5910 (jim_thompson5910):

you have to undo squaring to isolate 'a'

jimthompson5910 (jim_thompson5910):

what operation undoes squaring?

OpenStudy (anonymous):

I've never heard of it

jimthompson5910 (jim_thompson5910):

square roots undo squaring

jimthompson5910 (jim_thompson5910):

example: 6 squared = 6^2 = 6*6 = 36 square root of 36 = sqrt(36) = 6

OpenStudy (anonymous):

10.81

jimthompson5910 (jim_thompson5910):

\[\Large a^2 + b^2 = c^2\] \[\Large a^2 + 18^2 = 21^2\] \[\Large a^2 + 324 = 441\] \[\Large a^2 = 441 - 324\] \[\Large a^2 = 117\] \[\Large a = \sqrt{117}\] Now simplify

jimthompson5910 (jim_thompson5910):

I recommend you factor 117 into two numbers where one number is a perfect square.

OpenStudy (anonymous):

\[3\sqrt{13}\]

jimthompson5910 (jim_thompson5910):

hopefully you see how to get there?

OpenStudy (anonymous):

Yes I got it. Thank you so much!

jimthompson5910 (jim_thompson5910):

you're welcome

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