Posted by **Carol** on Monday, January 3, 2011 at 3:58pm.

Could someone please show me how

1 / ( 4 tan (x/2) + 2 )

is converted to:

(- sin (x/2) /( 2 sin (x/2) + cos (x/2))

TIA

Carol

- Trig -
**bobpursley**, Monday, January 3, 2011 at 4:10pm
lets check it at x=0, and x=PI/2

x=0: 1/4(1+2)=1/12

(-sin45/(2sin45+cos45)=-.707/(1.414+.707) does not equal 1/12

- Trig -
**bobpursley**, Monday, January 3, 2011 at 4:11pm
that was at x=90 deg, the identity did not hold. Now at x=0

1/4(0+2)=1/8

-0/(0+.7) does not equal 1/8

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