Q. 11. If
show that 
Q. 12. In the given figure, ABCD is rectangle with AD = 12 cm and DC = 20 cm. Line segment DE is drawn making an angle of 
with AD intersecting AB at E. Find the lengths of DE and AE.
Q. 13. If
and
, then prove that 
Q. 14. If
and 
then prove that 
Q. 15.
Q. 16.
Q. 17. If
Q. 18. If
