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Mathematics
9. Triangle and Its Angles
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Q6 of 69 Page 10

If one angle of a triangle is equal to the sum of the other two, show that the triangle is a right triangle.

If one of the angle of a triangle is equal to the sum of other two.

i.e. ∠B = ∠A + ∠C


Now, in


Sum of all angles of triangle is 180o


∠A + ∠B + ∠C = 180o


∠B + ∠B = 180o [Therefore, ∠A + ∠C = ∠B]


2∠B = 180o


∠B = 90o


Therefore, ABC is right angled triangle.


More from this chapter

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4

The angles of a triangle are arranged ascending order of magnitude. If the difference between two consecutive angles is 10°, find the three angles.

5

Two angles of a triangle are equal and the third angle is greater than each of those angles by 30°. Determine all the angles of the triangle.

7

ABC is a triangle in which ∠A = 72°, the internal bisectors of angles B and C meet in O. Find the magnitude of ∠BOC.

8

The bisectors of base angles of a triangle cannot enclose a right angle in any case.

Questions · 69
9. Triangle and Its Angles
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