Circle Clues SlidesCircle Secrets Angle & Arc Detective Training Central Angles 80° 80° The Same Rule The center angle is exactly the SAME as the arc. Angle = Arc Inscribed Angles 40° 80° The Half Rule The edge angle is HALF of the arc. Arc ÷ 2 = Angle Inside Angles ?° Arc 1 Arc 2 The Average Rule Add the arcs, then divide by 2. (Arc 1 + Arc 2) ÷ 2 Outside Angles ?° Big Small The Subtract Rule Subtract small from big, then divide by 2. (Big - Small) ÷ 2 Circle Formulas Circumference d r C = π × d C = 2 × π × r Area r A = π × r2 Split diameter in half first!
Angle Lab WorksheetAngle Lab Worksheet Name: __________________________ Date: ______________ Detective Training 1. Central Angle 82° Clue: SAME as the arc Angle = ________ 2. Inscribed Angle 60° Clue: HALF of the arc Angle = ________ 3. Inside Angle 70° 30° Clue: Add arcs, then ÷ 2 Step 1: ____________ Step 2 (÷ 2): ________ 4. Outside Angle 100° 40° Clue: Sub arcs, then ÷ 2 Step 1: ____________ Step 2 (÷ 2): ________ Reverse Clues: Find the Missing Arc 5. Find Arc 110° Arc = Angle Arc = ________ 6. Find Arc 45° Angle × 2 = Arc Arc = ________ Circle Reference Desk Circumference (Border) C = πd or 2πr Area (Inside Space) A = πr2 Lab Notes & Scratchpad
Lab Master KeyLab Master Key Complete Teacher Solutions & Reference Guide Official Key 1. Central 82° MATCH ARC Ans: 82° 2. Inscribed 60° 60 ÷ 2 Ans: 30° 3. Inside 70° 30° (70+30) ÷ 2 Ans: 50° 4. Outside 100° 40° (100-40) ÷ 2 Ans: 30° 5. Rev Arc 110° ARC = ANGLE Ans: 110° 6. Rev Arc 45° 45 × 2 Ans: 90° Circumference C = πd or 2πr Area A = πr2 Teacher Reference Master Key © Circle Secrets Laboratory