Dr. J's Maths.com
Where the techniques of Maths
are explained in simple terms.

Trigonometry - Sine Rule.
Test Yourself 2.


 

Basic - find the length of a side
(answer to 2 dps).		    
     
     
  XYZ is a triangle in which ∠XYZ = 45°, ∠YXZ = 30° and the side YZ = 10 cm.

Find the length of side XZ to the nearest millimetre.

  
     
Side not opposite    
     
     
Basic - find the size of an angle. 17.  
     
     
     
Angle not opposite.    
     
The ambiguous case. 25.

Find the value of the angle d° in the above triangle (to the nearest minute) - given that the angle is obtuse.

Answer.d° = 180° - 46° 4' = 133° 56'.		  
     
 

27. Let the angles in triangle ABC be x, y and z.

D is a point on BC such that AD bisects the angle at A.

Let BD = s and so DC = a - s

(i) In triangle ABD, show that .

(ii) Using triangle ADC, find the corresponding result.

(iii) Using both of the above results, prove that

.

(iv) State the result you have obtained in (iii) as a theorem (which is a very important theorem).