To find the measure angles B, C and F, you will need to know that the sum of all the angles in a triangle total 180 degrees and the sum of all the angles in a quadrilateral equal 360 degrees.
1. Start with what you know: angles I, E, and H needs to equal 180 (it is a straight line). 180 - 56 - 90 = 34 degrees.
H = 34 degrees
2. Angles H, G, and A must equal 180, so 180-34-38 = 108 degrees
G = 108 degrees.
3. Angles G and F must equal 180 degrees (straight line), so 180-108 = 72
F = 72 degrees
4. Angles E, D, F, and C must equal 360, so 360-180-72 = 108
C = 108 degrees
5. Angles J and D must add up to 180 (straight line); so 180-90=90
J = 90 degrees
6. Angles B, I, and J must add up to 180, so 180-56-90=34
B = 34 degrees
