+0  
 
+3
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3
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if pi/2 < x < pi and sinx = 2/5 then tanx = ؟

 Jul 27, 2014

Best Answer 

 #2
avatar+118587 
+11

I always draw the right angled triangle for these.  

x is one of the acute angles

2 is the opposite side, 5 is the hypotenuse.

Get the other side using pythagoras' Theorum

then read tanx of the triangle.

plus as Alan said it is in the second quad so it is negative. 

 Jul 27, 2014
 #1
avatar+33603 
+8

This is in the second quadrant where tan is negative, so tanx = -2/√(52-22) = -2/√21

 Jul 27, 2014
 #2
avatar+118587 
+11
Best Answer

I always draw the right angled triangle for these.  

x is one of the acute angles

2 is the opposite side, 5 is the hypotenuse.

Get the other side using pythagoras' Theorum

then read tanx of the triangle.

plus as Alan said it is in the second quad so it is negative. 

Melody Jul 27, 2014
 #3
avatar+1832 
+3

thanx for all 

 Jul 27, 2014

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