a red string of holiday lights blinks once every 3 seconds while a string of blue lgihts blink once every 4 seconds. how many ti
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Answer:
The length of DC in meters is ⇒ A
Step-by-step explanation:
In the circle O
∵ AB passing through O
∴ AB is a diameter
∵ D is on the circle
∴ ∠ADB is an inscribed angle subtended by arc AB
∵ Arc AB is half the circle
→ That means its measure is 180°
∴ m∠ADB = × 180° = 90°
In ΔADB
∵ m∠ADB = 90°
∵ AD = 5 m
∵ BD = 12 m
→ By using Pythagorase Theorem
∵ (AB)² = (AD)² + (DB)²
∴ (AB)² = (5)² + (12)²
∴ (AB)² = 25 + 144 = 169
→ Take square root for both sides
∴ AB = 13 m
∵ ∠ADB is a right angle
∵ DC ⊥ AB
∴ DC × AB = AD × DB
→ Substitute the lengths of AB, AD, and DB
∵ DC × 13 = 5 × 12
∴ 13 DC = 60
→ Divide both sides by 13
∴ DC = m
∴ The length of DC in meters is