SOLUTION: 1. tan^2 20 degree - sec^2 20 degree 2. cos^2(10 degree 5`) + sin^2 (10 degree 5`) 3. 2sec^2 2pie/7 cos^2 2pie/7

Algebra ->  Trigonometry-basics -> SOLUTION: 1. tan^2 20 degree - sec^2 20 degree 2. cos^2(10 degree 5`) + sin^2 (10 degree 5`) 3. 2sec^2 2pie/7 cos^2 2pie/7      Log On


   

Question 697348: 1. tan^2 20 degree - sec^2 20 degree
2. cos^2(10 degree 5`) + sin^2 (10 degree 5`)
3. 2sec^2 2pie/7 cos^2 2pie/7
Answer by god2012(113) About Me  (Show Source):
You can put this solution on YOUR website!
Solution :
1. tan%5E2+%2820%29-+sec%5E2+%2820%29+
+%28sin%5E2+%2820%29+-+1%29%2Fcos%5E2+%2820%29
-cos%5E2+%2820%29+%2F+cos%5E2+%2820%29+=+-1
2. cos%5E2%2810+degree+5%60%29+%2B+sin%5E2+%2810+degree+5%60%29
let 10 degree 5 = t
therefore, the equation becomes
cos%5E2+%28t%29+%2B+sin%5E2+%28t%29+=+1+
3. 2sec%5E2+%282pie%2F7%29+cos%5E2+%282pie%2F7%29
let 2pie/7 = t
therefore, the equation becomes
2sec%5E2+%28t%29+%2A+cos%5E2+%28t%29
=+%282%2Fcos%5E2+%28t%29%29+%2A+cos%5E2+%28t%29
because sec (t) = 1/cos (t)
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