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The position vectors of the vertices `A, B and C` of triangle are `hati+hatj, hatj+hatk and hati+hatk`, respectively. Find the unit vectors `hatr` lying in the plane of `ABC` and perpendicular to `IA`, where I is the incentre of the triangle. |
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Answer» Correct Answer - `vecr = pm (1)/(sqrt2)(hati +hatj)` Since `|vec(AB)|= |vec(BC)|= |vec(CA)|`, the incentre is same as the circumcentre, and hence IA is perpendicular of BC. Therefore, `vecr` is parallel to BC. `vecr= lamda (hati-hatj)` Hence, unit vector `vecr=pm (1)/(sqrt2)(hati-hatj)` |
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