SOLUTION: My teacher has not gone over this and I need help! The problem asks to express the following fraction as a cofunction of a complementary angle. If you know how to do this please sh

Algebra ->  Numeric Fractions Calculators, Lesson and Practice -> SOLUTION: My teacher has not gone over this and I need help! The problem asks to express the following fraction as a cofunction of a complementary angle. If you know how to do this please sh      Log On


   

Question 1158756: My teacher has not gone over this and I need help! The problem asks to express the following fraction as a cofunction of a complementary angle. If you know how to do this please show me the steps so I can understand how to do these types of problems. Thank you!
a). cos 3pi/8
b).tan 2
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

As the "co" in "cosine" implies, it means we are talking about the cofunction to sine.

Through the use of this cofunction identity
cos%28x%29+=+sin%28pi%2F2+-+x%29

we can say the following:
cos%28x%29+=+sin%28pi%2F2+-+x%29

cos%283pi%2F8%29+=+sin%28pi%2F2+-+3pi%2F8%29

cos%283pi%2F8%29+=+sin%284pi%2F8+-+3pi%2F8%29

cos%283pi%2F8%29+=+highlight%28sin%28pi%2F8%29%29

--------------------------------------------------------

Similarly,
tan%28x%29+=+cot%28pi%2F2+-+x%29

tan%282%29+=+cot%28pi%2F2+-+2%29

tan%282%29+=+cot%28pi%2F2+-+4%2F2%29

tan%282%29+=+highlight%28cot%28%28pi-4%29%2F2%29%29