Khan/khan-exercises — Issue #6886: Trig identities 1 - I dont'undersstand
Author: KhanBugz
Created: 2011-11-22 05:21:00+00:00
State: open
Labels: firefox, hard, xp

I work through the problem and get to the last two steps and cannot figure out how 1 - (sqrt2 over 2) squared becomes the sqrt of 2 over 2. I can understand taking the sqrt on both sides of the equation, but what happened to the +1?

I am totally lost on the arithmetic.

[trig_identities_1.html?seed=65&problem=0](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/trig_identities_1.html?seed=65&problem=0&debug)

[Answer timeline](http://sandcastle.khanacademy.org/media/castles/Khan:master/exercises/trig_identities_1.html?seed=65&problem=0&debug&activity=%5B%5B%22incorrect-activity%22%2C%22%5C%22None%20of%20the%20above.%5C%22%22%2C245%5D%2C%5B%22hint-activity%22%2C%220%22%2C0%5D%2C%5B%22hint-activity%22%2C%220%22%2C0%5D%2C%5B%22hint-activity%22%2C%220%22%2C1%5D%5D)

["None of the above."]

Mozilla/5.0 (Windows NT 5.1; rv:8.0) Gecko/20100101 Firefox/8.0

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