2. In A ABC, <B = 90°, AB= 13cm, AC= 21cm
BC=——–​

2 thoughts on “2. In A ABC, <B = 90°, AB= 13cm, AC= 21cm<br />BC=——–​”

1. Step-by-step explanation:

   • Here, In ∆ ABC
   • Angle B = 90°
   • So, ∆ABC IS A RIGHT ANGLE TRIANGLE.
   • Now, AB = 13 cm
   • AC = 21 cm
   • BC = ?
   • By pythagores theorem ,
   • Hypotenuse^2 = Base^2 + Perpendicular^2
   • AC ^2 = BC ^2 + AB^2
   • 21^2 = BC^2 + 13^2
   • 441 = BC^2 + 169
   • BC^2 = 441–169
   • BC = √272=16.5cm (approx)

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2. by pythagorous theorem,

   21²=13²+BC²

   441-169=BC²

   272=BC²

   BC=4√17

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