Answer :
Answer:
tanA/2.
Step-by-step explanation:
some trigonometric properties:
* tanA = sinA/cosA
* secA = 1/cosA
* cscA = 1/sinA
* cotA = cosA/sinA
1/sinA - cotA
1/sinA - cosA/sinA
1 - cosA / sinA
.... 1 - cosR / sinR = tan(R/2)
1 - cosA / sinA
= tanA/2.