Let’s solve each part step by step.
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First Problem:
We are given:
- ∠ABD = 40°
- ∠ABC = 28°
- We need to find ∠CBD
Look at the diagram (even though we don’t describe it, we can reason from the labels):
Point B is the vertex. Rays go out to A, C, and D. Since ∠ABD is the big angle from A to D, and ∠ABC is part of it (from A to C), then ∠CBD must be the rest — from C to D.
So:
∠CBD = ∠ABD - ∠ABC
∠CBD = 40° - 28° =
12°
✔ That makes sense — if you take away the smaller piece from the bigger piece, you get the leftover piece.
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Second Problem:
We are given:
- ∠EFG = 33°
- ∠GFH = 19°
- We need to find ∠EFH
Again, point F is the vertex. Rays go to E, G, H.
∠EFH is the total angle from E to H. It includes both ∠EFG and ∠GFH.
So:
∠EFH = ∠EFG + ∠GFH
∠EFH = 33° + 19° =
52°
✔ Adding the two parts gives the whole angle.
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Third Problem (Skateboard Ramp):
Original incline = 40°
She adjusts it to half the original incline.
So now:
New incline = 40° ÷ 2 =
20°
✔ Half of 40 is 20 — simple division.
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Final Answer:
∠CBD = 12°
∠EFH = 52°
New ramp incline = 20°
Parent Tip: Review the logic above to help your child master the concept of adding and subtracting angles worksheet.