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प्रश्न
Find:
a. BC
b. AD
c. AC
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उत्तर
a. In right ΔABC,
tan30° = `"AB"/"BC"`
⇒ `(1)/sqrt(3) = (10)/"BC"`
⇒ BC = `10sqrt(3)"cm"`.
b. In ΔABC, ∠C = 30° and ∠B = 90°
⇒ ∠A = 60°
Now, In ΔABD,
cos60° = `"AD"/"AB"`
⇒ `(1)/(2) = "AD"/(10)`
⇒ AD = 5cm
c. In ΔABC,
AC2
= AB2 + BC2
= `10^2 + (10sqrt(30))^2`
= 100 + 300
= 400cm
⇒ AC = 20cm.
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