Mark (✓) against the correct answer:
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 :

$(3 x)^{\circ}=(3 \times 18)=54^{\circ}$

$(7 x)^{\circ}=(7 \times 18)^{\circ}=126^{\circ}$

$(9 x)^{\circ}=(9 \times 18)^{\circ}=162^{\circ}$