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a) Here, sum of two non-adjacent angles: 52 + 25 = 77
Now, ∠3 = 180 - 77 [ sum of all angles in a triangle is 180 ]
so, ∠3 = 103
Now, ∠3 + ∠4 = 180 [ Supplementary angles ]
So, ∠4 = 180 - ∠3
∠4 = 180 - 103 = 77
∠4 = 77 [ which is sum of two non-adjacent angles ]
....Hence proved.
b) m∠4 = 77
[ Solved in previous section ]
Hope this helps!
