Question

77. If one angle of the triangle is greater than the
Sum of other two, show that the triangle is obtuse
angled.​

Answer 1

Let there be a triangle ABC
Angle A > B+C (Statement 1)
We know that,
A+B+C= 180
B+C= 180-A (Statement 2)
Putting value of B+C from statement 2 to statement 1, we get
A > 180-A
Adding A to both sides
A+A > 180-A+A
2A > 180
1/2 * 2A > 1/2* 180
A > 90
Therefore angle A is obtuse angle



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