To find the missing angle 'A' in each problem, we look at how the angles are arranged. In every diagram, there is one large angle (shown with a dotted orange arc) that is split into two smaller angles (shown with solid green and blue arcs).
The rule is simple: The two smaller angles add up to make the larger angle.
* If 'A' is one of the smaller parts, we
subtract the known small part from the large total.
* If 'A' is the large total, we
add the two smaller parts together.
Here is the step-by-step solution for each number:
1) The total is 133°. One part is 32°.
$133 - 32 = 101$
A = 101°
2) The total is 155°. One part is 44°.
$155 - 44 = 111$
A = 111°
3) The total is 149°. One part is 50°.
$149 - 50 = 99$
A = 99°
4) The total is 160°. One part is 50°.
$160 - 50 = 110$
A = 110°
5) The total is 107°. One part is 61°.
$107 - 61 = 46$
A = 46°
6) The total is 161°. One part is 36°.
$161 - 36 = 125$
A = 125°
7) The total is 124°. One part is 61°.
$124 - 61 = 63$
A = 63°
8) The total is 108°. One part is 50°.
$108 - 50 = 58$
A = 58°
9) Here, 'A' is the large total angle. The parts are 39° and 63°.
$39 + 63 = 102$
A = 102°
10) Here, 'A' is the large total angle. The parts are 30° and 115°.
$30 + 115 = 145$
A = 145°
11) The total is 148°. One part is 41°.
$148 - 41 = 107$
A = 107°
12) The total is 114°. One part is 38°.
$114 - 38 = 76$
A = 76°
Final Answer:
1. 101°
2. 111°
3. 99°
4. 110°
5. 46°
6. 125°
7. 63°
8. 58°
9. 102°
10. 145°
11. 107°
12. 76°
Parent Tip: Review the logic above to help your child master the concept of finding unknown angle measures worksheet.
