# Determine Whether the Triangle Having Sides (A − 1) Cm, 2Sqrta Cm and (A + 1) Cm is a Right-angled Triangle. - Mathematics

Determine whether the triangle having sides (a − 1) cm, 2sqrta cm and (a + 1) cm is a right-angled
triangle.

#### Solution

Let ABC be the Δ with

AB = (a – 1) cm BC = 2sqrta cm, CA = (a + 1) cm

Hence, AB2 = (a − 1)2 = a2 + 1 − 2𝑎

BC2 = (2sqrta)2 = 4a

CA2 = (a + 1)2 = a2 + 1 + 2a

Hence AB2 + BC2 = AC2

So Δ ABC is right angled Δ at B.

Concept: Application of Pythagoras Theorem in Acute Angle and Obtuse Angle
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#### APPEARS IN

RD Sharma Class 10 Maths
Chapter 7 Triangles
Exercise 7.7 | Q 21 | Page 121