Question

10)What is the number of degrees in the third angle of the triangle? ___;80°;22°

Answer 1

Given :–

• First angle = 80°
• Second angle = 22°

To Find :–

• Third angle of a triangle.

Solution :–

Let,

The third angle be x.

We know that,

Sum of all the angles of a triangle = 180°

i.e.

• ∠1 + ∠2 + ∠3 = 180° --------(1)

So here given that,

• ∠1 = 80°
• ∠2 = 22°

Now, put the given values in (1).

⟹ 80° + 22° + x = 180°

⟹ 102° + x = 180°

⟹ x = 180° – 102°

⟹ x = 78°

Hence,

The third angle of a triangle is 78°.

Check :–

Put all the values in (1).

So,

⟹ ∠1 + ∠2 + ∠3 = 180°

• ∠1 = 80°
• ∠2 = 22°
• ∠3 = 78°

⟹ 80° + 22° + 78° = 180°

⟹ 80° + 100° = 180°

⟹ 180° = 180°

Hence, the L.H.S. and the R.H.S. are equal.

So, the answer is correct.