Step-by-step explanation:
L.H.S=(1-cosB)(1+cosB)
=(1-cos^2B). {using (a+b) (a-b)=(a^2-b^2)in second step}
=sin^2B
=1/cosec^2B
Therefore,L.H.S=R.H.S proved
Answer:
-1113
Step-by-step explanation:
You apparently want the sum of the 14-term arithmetic sequence ...
-21, -30, -39, ..., -138
The average term is ...
(-21 -138)/2 = -79.5
so the sum of the 14 terms is ...
(14)(-79.5) = -1113
Answer:
15
Step-by-step explanation:
195/13=15
