20 In the diagram what is the sum of the measure of angles 1
Solution
For a 5-sided polygon (pentagon) this is (5-2)*180° = 3*180°=540°
 Since all 5 angles of a regular pentagon are equal, each
 interior angle of the regular pentagon is 540/5 = 108°
 Its suppplement is found by subtracting 180°-108°=72°
 That 72° angle is one of the base angles of an isosceles
triangle. So we\'ll mark the other base angle 72° also
 Now we can find the angle at the top point of the star by
 adding the two equal base angles and subtracting from 180°.
72° + 72° = 144°
 180° - 144° = 36°
So each point of the star is 36°
In a regular pentagram (five pointed star) each point is 36o so the sum of all angle is 180o.
So, the angle(1+2+3+4+5) = 5 x 36 = 180o
16. In the given figure the angles are not defined in which position they are
this could be solved by sector formula

