4 ΔDEF = 64 ⇒ ΔDEF =  64  = 16 sq. units 
4 
⇒ 4 ΔPQR = 16 =  16  = 4 sq. units. 
4 
⇒ GS =  1  × 9 = 3 cm 
3 
⇒ RG =  2  × 6 = 4 cm 
3 
∴ RS =  3^{2} + 4^{2}  =  9 + 16  = 5 cm 
= AB^{2}+ AC^{2} + 2 AB .  1  AC 
2 
[∵ AD = AC cos 60° =  1  AC ] 
2 
8 cm  =  12 cm  =  AC 
sin Θ  sin 59°  sin (121° – Θ) 
Thus,  8 cm  ≈  12 cm 
sin Θ  sin 60° 
or, sin Θ ≈  8 cm × sin 60°  =  2  × 

=  1  = 0.577  
12 cm  3  2  3 
∴ cos Θ = 

= 

= 

× 

–  –1  ×  1  =  1  +  1  = 0.996  
2  2  3  2 

Now,  AC  ≈  8 cm 
sin (121° – Θ)  sin Θ 
or, AC =  8 cm sin(120° – Θ)  =  8 × 0.996  = 13.809 ≈ 14 cm 
sin Θ  0.577 
BC =  (20 + 36)^{2} + (15 – 15)^{2}  = 56 
AB =  (20)^{2} + (15)^{2}  = 25 
AC =  36^{2} + 15^{2}  = 39 
α =  56 × 0 + 39 × 20 + 25(–36) 
56 + 39 + 25 
=  –900 + 780  =  –120  = –1 
120  120 
β =  56 × 0 + 39 × 15 + 25(15)  = 8 
56 + 39 + 25 