1. cos(-1710)=cos(-1710+5x360)
why do we take 5. in this solution.

Asked by Anju Sharma | 1st Jul, 2014, 08:55: PM

Expert Answer:

S i n e space a n d space cos i n e space a r e space p e r i o d i c space f u c n t i o n s space w i t h space p e r i o d space 2 straight pi. Therefore space the space value space of space straight a space trigonometrical space ratio space for space any space angle space is space same space as space the space value space of space trigonometrical function space for space the space same space angle space in space terms space of space positive space acute space angle. Here comma space the space angle space given space is space the space negative space angle space greater space than space 2 straight pi equals 360. We space need space to space convert space minus 1710 degree space to space straight a space positive space acute space angle. So space let space us space express space the space angle space in space the space form space straight alpha equals nπ plus-or-minus straight theta comma space where space straight theta space is space an space acute space angle. Therefore cos open parentheses minus 1710 degree close parentheses equals cos open parentheses 10 straight pi minus 1710 degree close parentheses equals cos open parentheses 90 degree close parentheses equals 0

Answered by Vimala Ramamurthy | 2nd Jul, 2014, 09:09: AM