The number of different groups can be found by finding 9C3 (Using combinations)
We will find combinations from n = 9 to r = 3
Therefore, 9C3 = 9!/6!*3! = (9*8*7*6!)/(6!*3*2)
= 3*4*7
= 84 ways.
Answer: Angle 2 = 47 degree
Explanation:
Proof that triangle ACB ~ triangle CBD
Angle ABC = Angle CBD (same angle)
If one pair of the angle is the same then the other pair should also be equal because both the triangle are Isosceles.
=> angle ACD = Angle CDB
Therefore, triangle ACB ~ triangle CBD (AA)
=> angle C = Angle A
But angle A = 47 degree
Therefore, Angle C = Angle 2 = 47 degree