If sina=-5/13 , and 3/2 < a< 2 what is cosine a and tan a

Hello from MrBillDoesMath!

-5/12

Discussion:

if  sin(a) = -5/13 then the underlying triangle is a  5, 12, 13 right triangle. From the Question, the angle lies in the third quadrant.

Hence cos(a) = 12/13 and

tan(a) = sin(a)/cos(a) = (-5/13)/ (12/13) = -5/12

Regards,  

MrB

P.S.  I'll be on vacation from Friday, Dec 22 to Jan 2, 2019. Have a Great New Year!

answer: all of the odd numbers were opened

the first person was the one that was opening all of the lockers. since one is odd, this causes all of the odd number lockers to be opened in the end.