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asked Feb 23, 2020 60.5k views

1 Answer

Gufran · Answer 1 · 2020-03-01T03:40:49+0000

Answer:

$\phi=\theta a2$

Explanation:

see the attached figure to better understand the problem

we know that

In the figure ABCD

$m<ADC=\theta a1$

$m<DAB=90\°$

$m<ABC=90\°$

$m<DCB=90\°+\phi$

Remember that the sum of the internal angles in a quadrilateral is equal to
$360\°$

so

$\theta a1+90\°+90\°+90\°+\phi=360\°$

$\theta a1+\phi=90\°$ -----> complementary angles

and

$\theta a1+\theta a2=90\°$ -------> complementary angles too

so

$\phi=\theta a2$