Question 744730
If sec x = -sqrt10 with 180 degrees less than or equal to x less than or equal to 270 degrees, find the following and write your answer in an exact form. 
A. Sin(2x) 
B. Cos(x/2) 
***
{{{sec(x)=-sqrt(10)}}} (180º ≤ x ≤ 270º)
{{{cos(x)=1/sec(x)=-1/sqrt(10)}}}
{{{sin(x)=sqrt(1-cos^2(x))=sqrt(1-(1/10))=sqrt(9/10)=3/sqrt(10)}}}
..
A. {{{sin(2x)=2sin(x)cos(x)=2(3/sqrt(10))*(-1/sqrt(10))=6/10=0.6}}}
.. 
B. {{{Cos(x/2)=sqrt((1+cos(x))/2)=sqrt(((1-(1/sqrt(10)))/2)))}}} 
={{{sqrt((sqrt(10)-1)/(2sqrt(10)))}}}