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January 21, 2017
Posted by **Moe** on Saturday, April 27, 2013 at 9:51pm.

- Algebra 2/ Trigonometry -
**Damon**, Saturday, April 27, 2013 at 10:59pmquadrant 2

cos 2y = 1 - 2 sin^2 y

but sin y = 3/5 (3 4 5 triangle)

cos 2 y = 1 - 2 (3/5)

= 1 - 6/5

= -1/5 - Algebra 2/ Trigonometry -
**Reiny**, Sunday, April 28, 2013 at 5:36amlast 3 lines should be

cos (2y) = 1 - 2(3/5)^2

= 1 - 18/25 = 7/25 or .28 - Algebra 2/ Trigonometry -
**Damon**, Sunday, April 28, 2013 at 8:04amWhoops, thank you