Q. 45.0( 1 Vote )

# Let’s try to find out the answer to the questions give below studying the figure beside.

**i.** Let’s write the names of two complementary angles.

**ii.** Let’s write the names of two supplementary angles.

**iii.** Let’s write the names of two vertically opposite angles.

Answer :

i. Complementary angles is defined as those pairs of angles which sum up to 90°.

In the above figure, OM is the angle bisector.

Ray OD is perpendicular to line AB.

So ∠AOM + ∠MOD = 90°.

Hence ∠AOM and ∠MOD are two complementary angles.

ii. Supplementary angles can be defined as those pairs of angles which sum up to 180°.

In the above figure,

∠AOD = 90° = ∠BOD ………. (as OD is perpendicular to line AB)

So ∠AOD + ∠BOD = 180°.

Similarly ray CO is perpendicular to line AB.

So ∠AOC + ∠BOC = 180°

So, the two pairs of supplementary angles are ∠AOD & ∠BOD and ∠AOC & ∠BOC

iii. In the above figure,

AB and CD are two straight lines intersecting at point O.

∠AOD is lying opposite to ∠BOC.

Similarly, ∠BOD is lying opposite to ∠AOC.

Hence ∠AOD and ∠BOC form the first pair of vertically opposite angles.

∠AOC and ∠BOD forms the second pair of vertically opposite angles.

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Let’s try to write the measurement of the angles from the figure given below:

∠TOS=20°

∠POQ=60°

∠POT=?

∠ROP=?

∠QOS=?

West Bengal - Mathematics

Let’s try to write the measurement of the angles from the figure given below:

∠1=35°

∠2=?

∠3=?

∠4=?

write.

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If two straight lines intersect each other four angles are formed. Let’s prove that the sum of measurement of the four angles is four right angles.

West Bengal - MathematicsLet’s write the measurement of ∠BOD, ∠BOC and ∠AOC.

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Let’s prove that internal and external bisectors of an angle are perpendicular to each other.

West Bengal - MathematicsTirtha draws two straight lines PQ and XY which intersect at O. Let’s measure the vertically opposite angles by protractor.

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