Question:
Mark (✓) against the correct answer:
The angles of quadrilateral are in the ratio 1 : 3 : 7 : 9. The measure of the largest angle is
(a) 63°
(b) 72°
(c) 81°
(d) none of these
Solution:
(d) none of the these
Let the angles be $(x)^{\circ},(3 x)^{\circ},(7 x)^{\circ}$ and $(9 x)^{\circ}$.
Sum of the angles of the quadrilateral is $360^{\circ}$.
$x+3 x+7 x+9 x=360$
$20 x=360$
$x=18$
Angles :
$(3 x)^{\circ}=(3 \times 18)=54^{\circ}$
$(7 x)^{\circ}=(7 \times 18)^{\circ}=126^{\circ}$
$(9 x)^{\circ}=(9 \times 18)^{\circ}=162^{\circ}$