Question

Given that tan a = -sqrt5 / 2 , where a is an obtuse angle, find the value of sin a/2 without using calculator

Answer 1

Well \[\Large tan \theta=\frac{sin\theta}{cos\theta}\]
So you have \[\Large \frac{-\sqrt{5}}{2}\] Well you have the same situation here where you can find the sin

Answer 2

Sin=numerator
Cos=denominator

Answer 3

do you have any idea to calculi it without calculator ?

Answer 4

He didn't see this prob yet but @jhonyy9 was that a worng approach to guiding ihm to hte answer?

Answer 5

him to the *

Answer 6

ok ,you have any idea to calculi it ,?so than how ?

Answer 7

Are you talking to me?

Answer 8

yes sure

Answer 9

Unless he made a typo with writng sin a/2.....Then the sin is -sqrt5 cause the cos which is 2, you divide it to get the tan

Answer 10

in what quadrant will has cosinus value of 2 ,do you know it ?

Answer 11

Well this has to be in the 4th quadrant since sin is negative and cos is positive and in order for cos to be positive, both sin/cos have to be pos or sin is negative alone