Here, I will set out to prove that an obtuse angle is equal to 90 degrees.....

Follow the diagram.....Here is the proof...

Consider a rectangle ABCD. Draw an arc CE with BC as radius and centre at B. Now draw perpendicular bisectors to AB at G and to DE at H. Let them meet at M.

We can prove that triangle AGM and triangle BGM are congruent by SAS test. Similarly we can prove that triangle DHM and triangle EHM are congruent(by SAS test).

Thus, l(AM)=l(BM) (Corresponding sides of congruent triangles AGM and BGM) l(ME)=l(MD) (Corresponding sides of congruent triangles DHM and EHM)

l(AD)=l(BC)=l(EB) (By construction)

Therefore, triangle MAD is congruent to MBE by SSS test. So, angle DAM=angle EBM (corresponding angles of congruent triangles MAD and MBE)

And,

angle GAM=angle GBM (corresponding angles of congruent triangles GAM and GBM)

angle DAM - angle GAM = angle EBM - angle GBM angle DAG = angle EBG

Since angle DAG is 90 degrees and angle EBG is clearly obtuse, 90 degrees= Obtuse angle!!!!!!!!!!

So now choose the following options...

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