How do you prove cscx = sec(pi/2 - x)cscx=sec(π2x)?

2 Answers
Mar 29, 2018

Since this is an identity,

the relation is true for all values of x

Explanation:

Given:

cscx=sec(pi/2-x)cscx=sec(π2x)

cscx=1/sinxcscx=1sinx

sec(pi/2-x)=1/cos(pi/2-x)sec(π2x)=1cos(π2x)

Thus,

1/sinx=1/cos(pi/2-x)1sinx=1cos(π2x)

cos(pi/2-x)=sinxcos(π2x)=sinx

Since this is an identity,

the relation is true for all values of x

Mar 29, 2018

See below

Explanation:

Using:
secx=1/cosxsecx=1cosx
1/sinx=cscx1sinx=cscx
cos(x-y)=cosxcosy+sinxsinycos(xy)=cosxcosy+sinxsiny

Start:
cscx=sec(pi/2-x)cscx=sec(π2x)

cscx=1/cos(pi/2-x)cscx=1cos(π2x)

cscx=1/(cos(pi/2)cosx+sin(pi/2)*sinx)cscx=1cos(π2)cosx+sin(π2)sinx

cscx=1/(cancel(0*cosx)+1*sinx)

cscx=1/sinx

cscx=cscx