7th Class
Mathematics
Mensuration
Question Bank
Mensuration
question_answer
The two adjacent sides of a parallelogram are 4 cm and 9 cm. The ratio of its altitudes is
A)21 : 22
B)4 : 9
C)16 : 81
D)11 : 37
Correct Answer:
B
Solution :
Let ABCD be the given parallelogram. If\[\angle DAB\]equal to\[\theta \], then\[\angle DCB\]will also be equal to\[\theta \]. DM and DN are the two altitudes. Now, in right angled triangle AMD, \[DM=4\,\,\sin \theta \] ...(1) Similarly, in right angled triangle CND, \[DN=9\,\,\sin \theta \] ...(2), From equations (1) and (2), \[\frac{DM}{DN}=\frac{4\sin \theta }{9\sin \theta }=\frac{4}{9}.\]