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September 16, 2014

September 16, 2014

Posted by **Sira** on Thursday, January 10, 2013 at 2:29am.

1) sin^2θ - cos^2θ = 2 sin^2θ - 1

- Trigonometry -
**Godwin**, Thursday, January 10, 2013 at 3:04amsin^2x + cos^2x = 1

from the above,we make cos^2x the subject of the formula:

cos^2x = 1- sin^2x......................(1)

substituting the above into the left hand side of original equation:

sin^2x - ( 1 - sin^2x )

expanding the bracket and noting that - times - equals +

sin^2x - 1 + sin^2x

rearranging:

2sin^2x - 1.

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