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In which one of the following triangles ...

In which one of the following triangles does the orthocentre lie in the exterior of the triangle.

A

`Delta ABC`, where in, `angle A = angle B = angle C = 60^@`

B

`Delta PQR`, wherein, `angle P = 40^(@) , angle Q = 30^(@) , angle R = 110^(@)`

C

`Delta XYZ`, wherein, `angle X = 80^(@), angle Y = 60^(@), angle Z = 40^(@)`

D

`Delta DEF`, wherein , `angle D= 52^(@), angle E = 90^(@), angle F = 38^(@)`

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The correct Answer is:
To determine in which triangle the orthocenter lies outside the triangle, we need to understand the properties of the orthocenter in relation to the angles of the triangle. ### Step-by-Step Solution: 1. **Understanding the Orthocenter**: The orthocenter of a triangle is the point where the three altitudes intersect. The position of the orthocenter depends on the type of triangle: - In an acute triangle, the orthocenter lies inside the triangle. - In a right triangle, the orthocenter lies at the vertex of the right angle. - In an obtuse triangle, the orthocenter lies outside the triangle. 2. **Identifying the Type of Triangle**: To find out in which triangle the orthocenter is outside, we need to look for an obtuse triangle. An obtuse triangle has one angle greater than 90 degrees. 3. **Analyzing the Given Angles**: The problem mentions angles: - Angle P = 40 degrees - Angle Q = 30 degrees - Therefore, Angle R = 180 - (Angle P + Angle Q) = 180 - (40 + 30) = 110 degrees. 4. **Determining the Type of Triangle**: Since Angle R is 110 degrees, which is greater than 90 degrees, triangle PQR is an obtuse triangle. 5. **Conclusion**: Since triangle PQR has an obtuse angle, the orthocenter of triangle PQR lies outside the triangle. ### Final Answer: The orthocenter lies outside the triangle PQR.
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S CHAND IIT JEE FOUNDATION-TRIANGLES-Question Bank- 18
  1. The given figure shows two overlapping triangles. The value of a - b i...

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  2. D, E, F are the mid points of BC, CA and AB of Delta ABC. If AD and B...

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  3. Consider the following statements relating to the congruency of two ri...

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  4. AB bot BC , BD bot AC and CE bisects angle C. angle A = 30^(@). Then w...

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  5. In Delta ABC, angle B is a right angle, AC = 6 cm, D is the mid point ...

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  6. If the sides of a right triangle are x , x + 1 and x -1, then the hypo...

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  7. The degree measure of each of the three angles of a triangle is an int...

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  8. In a Delta ABC right angled at B, which statement is true?

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  9. If PL , QM and RN are the altitudes of Delta PQR whose orthocentre is ...

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  10. In Delta ABC medians BE and CF intersect at G. If the straight line AG...

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  11. If the angles of a triangle are in the ratio 1:2:3, find the ratio bet...

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  12. If the angles of a triangle are in the ratio 5 : 3 : 2, then the trian...

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  13. Delta ACB ~= Delta DFE. Find angle F

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  14. P is the incentre of Delta ABC. If angle CAB = 66^(@), and angle CPY =...

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  15. A man goes to a garden and runs in the following manner: From the star...

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  16. In the given figure, ABC is a triangle in which BC is produced to D. I...

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  17. If ABCD is a square, X is the mid point of AB and Y is the mid point o...

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  18. In a Delta PQR, the sides PQ and PR and are produced to S and T respec...

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  19. In a Delta ABC, angle C = 110^(@). Which one of the following statemen...

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  20. In which one of the following triangles does the orthocentre lie in th...

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