How do you graph, identify the domain, range, and asymptotes for y=(1/2)sec2(x-pi/2)+1y=(12)sec2(xπ2)+1?

1 Answer
Jul 21, 2018

See graph and explanation.

Explanation:

y = 1/2 sec( 2 ( x - pi/2 ) + 1 = 1/2 sec( 2 x - pi ) + 1y=12sec(2(xπ2)+1=12sec(2xπ)+1

= 1/2 sec( pi - 2 x ) + 1=12sec(π2x)+1

= 1/2 sec ( 2 x ) + 1=12sec(2x)+1.

= 1/(2 cos ( 2 x )) + 1=12cos(2x)+1.

The period = period of cos( 2 x ) = 2pi )/2 = pi2π)2=π.

The asymptotes are given by cos ( 2 x ) = 0cos(2x)=0

rArr 2 x = ( 2 k + 1 )pi/2 rArr x = ( 2 k + 1 )pi/42x=(2k+1)π2x=(2k+1)π4,

k == 0, +-1, +-2, +-3,... So, the domain is

x in ...U (-5/4pi, -3/4pi ) U (-3/4pi, -pi/4 ) U (-pi/4, pi/4 )

U ( pi/4, 3pi/4 ) U (3pi/4, 5pi/4 ) U ...

Range is given by

y notin ( -1/2 + 1,1/2 + 1 ) = ( 1/2, 3/2 ).

See illustrative graph, indicating range and two asymptotes,

near O..
graph{(2(y-1) cos (2x)-1)(y-1/2)(y-3/2)(x^2-(pi)^2/16 )=0[-8 8 -3 5]}