please give me correct answer
Answers
Answer :-
- 165°.
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⋆Question :-
- The four angles of a pentagon are 40°, 75° , 125° and 135° . The measure of the fifth angle is :-
- 165°
- 170°
- 160°
- 175°
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Answer :-
- The four angles of a pentagon are 40°, 75° , 125° and 135° . The measure of the fifth angle is :-
- 165° ✔
- 170°
- 160°
- 175°
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Given :-
- Four angles of a pentagon (Five sided figure) that are 40°, 75° , 125° and 135°
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Find :-
- Fifth angle of the pentagon .
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We know :-
- Sum of interior angles of pentagon is 540° .
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⋆Solution :-
Let the fifth angle be X .
∴ X + 40° + 75° + 125° + 235° = 540° [Sum of interior angles of pentagon is 540° ].
⟹ X + 375° = 540°
⟹ X = 540° - 375°
⟹ X = 165° .
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Regular Polygon Name Each
interior angle
- Triangle • 60°
- Quadrilateral • 90°
- Pentagon • 108°
- Hexagon • 120°
- Septagon • 128 . 57°
- Octagon • 135°
- Nonagon • 140°
- Decagon • 144°
☆Note :- It is written each interior angle and not all . So, Don't be confused by seeing that pentagon is 540° , then how here it is 108° . It I because in 540° we multiplied 5 with 108° see 108° multiply 5 = 540° .
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How , 540° came :-
We know it is pentagon that means which has 5 sides .
So, let
n be No. of sides then, Using the formula
Sum of all angles of a Polygon
➨2n-4 ✖ 90°
Here , n = 5
➨2✖5 -4 ✖ 90°
➨10-4✖90°
➨6✖90°
➨ 540°