Question

8) If two angles of a triangle are 55 degrees and 65 degrees then the 3rd
angle =
a) 120 degrees
b) 180 degrees
c) 60 degrees​

Answer 1

Answer:

c) 60° is the correct answer.

Step-by-step explanation:

Given,

• $\angle{1st}$ = 55°
• $\angle{2nd}$ = 65°

To find,

• Measure of the 3rd angle.

Knowledge Required,

• The sum of all the angles of a triangle is 180°.

Finding the 3rd angle.

$\angle{1st}$+$\angle{2nd}$+$\angle{3rd}$ = 180°

⇒55°+65°+$\angle{3rd}$ = 180°

⇒ 120° + $\angle{3rd}$ = 180°

⇒$\angle{3rd}$ = 180° - 120°

⇒$\angle{3rd}$ = 60°

.°. $\angle{3rd}$ = 60°

Hence, option c) 60° is the correct answer.

Answer 2

QUESTION:-

__________________

If two angles of a triangle are 55 degrees and 65 degrees then the 3rd

angle =

a) 120⁰

b) 180⁰

c) 60⁰

Answer:- 60⁰

Explanation:-

__________________

•Let the all three angles of the triangle be ∠x ,∠y and ∠z

Then,

∠x=55⁰

∠y=65⁰

∠z=?

Thus these all are angles of only one triangle

↣By angle sum property of triangle

⇢ ∠x+∠y+∠z=180⁰

⇢ 55⁰+65⁰+∠z=180⁰

⇢ 120⁰+∠z=180⁰

⇢ ∠z=180⁰-120⁰

⇢ ∠z=60⁰

Therefore, 60⁰ (option c) is the required angle .