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In an isosceles triangle ABC with AB = AC = 13 cm and BC = 10 cm, the altitude from A to BC is
A8 cm
B10 cm
C15 cm
D12 cm
Answer & Solution
Correct answer: D. 12 cm
1. Foot of altitude D bisects BC (isosceles), so BD = 5.
2. By Pythagoras in triangle ABD: AD squared = 13 squared minus 5 squared = 169 minus 25 = 144.
3. AD = 12 cm.
_Source: NCERT Class 10 Mathematics, Ch 6 "Triangles", §6.5_
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