How to find the perimeter of a rhombus ABCD if the angle is A = 60 degrees BD = 9 cm

1.Considering that the sum of the angles adjacent to one side of the rhombus is 180 °, we calculate

the value of the angle at the vertex B:

180 ° – 60 ° = 120 °.

2. We calculate the value of the AВD angle, taking into account that the ВD diagonal divides the angle at the top B

in half:

AВD angle = 120 °: 2 = 60 °.

3. Angle ADВ = 180 ° – 60 ° – 60 ° = 60 °. Since all the inner angles of the AВD triangle are equal to 60 °,

this triangle is equilateral. Therefore ВD = AB = AD = 9 cm.

4. We calculate the perimeter of the rhombus:

9 x 4 = 36 cm.

Answer: the perimeter of the rhombus is 36 cm.