Q9 of 45 Page 27

Using the information in figure 3.12, find the measures of ∠a, ∠b and ∠c.

In the given triangle


a + b + c = 180° …………(1)


c + 100° = 180° ……….(2) [angles in linear pair]


⇒ c = 180° - 100°


⇒ c = 80°


b = 70° ……………..(3) [opposite angles are equal]


Putting value of b and c in (1)


⇒ a + 70° + 80° = 180°


⇒ a = 180° - 150°


⇒ a = 30°


More from this chapter

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7

In ΔABC, bisectors of ∠A and ∠B intersect at point O. If ∠C= 700 Find measure of ∠AOB.

 8

In Figure 3.11, line AB || line CD and line PQ is the transversal. Ray PT and ray QT are bisectors of ∠BPQ and ∠PQD respectively.

Prove that ∠PTQ = 90°.


 10

In figure 3.13, line DE || line GF ray EG and ray FG are bisectors of ∠DEF and ∠DFM respectively.

Prove that,


i. ∠DEG = 1/2∠EDF


ii. EF =FG.


 1

In each of the examples given below, a pair of triangles is shown. Equal parts of triangles in each pair are marked with the same signs. Observe the figures and state the test by which the triangles in each pair are congruent.