Question

Find the length of the perimeter of a regular decagon which surrounds a circle of radius 12 cm​

Answer 1

Answer:

24

Step-by-step explanation:

beacuse they are half and they are full

Answer 2

The Perimeter of decagon would be 74 cm

1) Consider a regular decagon ABCDEFGHIJ inscribed in a circle of radius 12 cm.

2) Join the lines AF,BG,CH,DI,EJ

3) Each of these lines would be of length 24 cm because they are diameters of the circle.

4) These lines would intersect at point O which is center of the circle.

5) OA,OB, OC, ...... OJ would be 12 cm.

6) In triangle OAB, OA = 12 cm, OB = 12 cm and Angle AOB = 360/10 = 36

7) Using cosine rule, we can find the third side as

AB² = OA²+OB²-2AB cos AOB = 55

AB = 7.4 cm

8) The perimeter of decagon would be 7.4 *10 = 74 cm.