What is m angles ABD in the figure shown?

∠ ABD = 19°

Step-by-step explanation:

Since AB and BC are congruent, then Δ ABC is isosceles and the base angles are congruent, that is

∠ BAD = ∠ BCD = 71° , thus

∠ ABC = 180° - (71 + 71) ← angle sum of triangle

∠ ABC = 180° - 142° = 38°

DB is an angle bisector , thus

∠ ABD = 0.5 × 38° = 19°

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

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