TRIGONOMETRY 



6. tanh" 1 tan x = \ gd 2x. 



7. tan" 1 tanh x = \ gd" 1 2x. 



SOLUTION OF OBLIQUE PLANE TRIANGLES 



50 



a, b, c = Sides of triangle, 



<*> ft 7 = angles opposite to a, b, c, respectively, 

 A = area of triangle, 

 s =i(a + b + c). 



Given Sought Formula 



a,b,c' a 



cos a. 



20C 



A A = VW 1 



. Q b sin a 

 a, b, a p sm p = 



5(5 - a) 

 + 6 2 - a 2 



When a>, jS< and but one value results. When b>a 



/3 has two values. 



7 = 180 - (a + 0). 

 a sin 7 



x, 

 a, a, a b 



7 7= 180- (a+j3). 



_ a sin 7 _ a sin (a + 

 sin a sin a 



