Let’s solve this step by step.
We are given a quadrilateral with points A, B, C, D. There’s a right angle at point C (marked with the square symbol). Also, there’s an exterior angle of 68° at point A, and two angles labeled in terms of y: one is 2y at point B, and another is y + 48° at point D (this is an exterior angle).
First, let’s find the interior angle at point A.
The 68° angle shown is outside the shape — it’s adjacent to the interior angle at A. Since they form a straight line, they add up to 180°.
So, interior angle at A = 180° - 68° = 112°
Now, look at point D. The angle marked as y + 48° is also an exterior angle. That means the interior angle at D is:
Interior angle at D = 180° - (y + 48°) = 132° - y
At point C, we have a right angle → that’s 90°.
At point B, the interior angle is given as 2y.
Now, remember: the sum of all interior angles in any quadrilateral is always 360°.
So, let’s write the equation:
Angle A + Angle B + Angle C + Angle D = 360°
Plug in what we know:
112° + 2y + 90° + (132° - y) = 360°
Now simplify:
Combine constants: 112 + 90 + 132 = 334
Combine y terms: 2y - y = y
So:
334 + y = 360
Subtract 334 from both sides:
y = 360 - 334 = 26
✔ Let’s double-check:
If y = 26,
- Angle at B = 2y = 52°
- Exterior angle at D = y + 48 = 74° → so interior angle at D = 180 - 74 = 106°
- Angle at A = 112° (as calculated)
- Angle at C = 90°
Sum: 112 + 52 + 90 + 106 = 360° → Correct!
Final Answer:
26
Parent Tip: Review the logic above to help your child master the concept of interior and exterior angles worksheet.