Question

Use an appropriate Half-Angle Formula to find the exact value of the expression.
cos
9π
8

Answer 1

thats cos (9pi/8)

Answer 2

yea sorry

Answer 3

\[(1-\cos \pi/6)/\sin \pi/6\]

Answer 4

\[\cos()\frac{ 9{\pi} }{ 8 }=\cos(\frac{ 405 }{ 2 })=\cos(\frac{ 360+45 }{ 2 })=\cos(180+\frac{ 45 }{ 2 })\]
\[=\cos(180)\cos(45/2)-\sin(180)\sin(45/2)\]
\[=-\cos(45/2)\]

Answer 5

\[\cos(45/2)=\sqrt{\frac{ \cos(45)+1 }{ 2 }}\]

Answer 6

huh?