Question

( A B C D ) is a cyclic quadritateral
HS sum of all interier angles of a triangle add up to ( 180^{circ} )
[
begin{array}{c}
therefore 2 K+3 K+5 K=180^{circ}
10 K=180^{circ}
K=18^{circ}
end{array}
]
In a cyclic quadribateral opposite interior angles are prappor supplementaly
[
begin{aligned}
therefore & angle A+angle C=180
& angle A+5 K=180
end{aligned}
]
( angle A+90=180 cdotleft(K=18^{circ}right) )
( angle angle A=90^{circ} )

# 17. If ABCD be a cyclic quadrilateral, then what will be the value of ZA? ТВ 3K oak (1) 90° (3) 110° (2) 80° (4) 120°

Solution