Tag: triangles

Triangles | Chapter 6 Exercise 6.5 Question 17:  Tick the correct answer and justify: In ∆ABC, AB =  cm, AC = 12 cm and BC = 6 cm.    The angle B is: (A) 120°           (B) 60°          (C) 90°            (D) 45° Solution: Detailed explanation of exercise 6.5 question 17 is given in the below image and YouTube […]

Triangles | Chapter 6 Exercise 6.5 Question 16:  In an equilateral triangle, prove that three times the square of one side is equal to four times the square of one of its altitudes. Solution: Detailed explanation of exercise 6.5 question 16 is given in the below image and YouTube video. Next Post

Triangles | Chapter 6 Exercise 6.5 Question 15:  In an equilateral triangle ABC, D is a point on side BC such that BD = BC. Prove that 9 AD2 = 7 AB2. Solution: Detailed explanation of exercise 6.5 question 15 is given in the below image and YouTube video. Next Post

Triangles | Chapter 6 Exercise 6.5 Question 14:  The perpendicular from A on side BC of a ∆ABC intersect BC at D such that DB = 3. Prove that 2 AB2 = 2 AC2 + BC2 Solution: Detailed explanation of exercise 6.5 question 14 is given in the below image and YouTube video. Next Post

Triangles | Chapter 6 Exercise 6.5 Question 13:  D and E are points on the sides CA and CB respectively of a triangle ABC right angled at C. Prove that AE2 + BD2 = AB2 + DE2 Solution: Detailed explanation of exercise 6.5 question 13 is given in the below image and YouTube video. Next Post

Triangles | Chapter 6 Exercise 6.5 Question 12:  Two poles of heights 6 m and 11 m stand on a plane ground. If the distance between the feet of the poles is 12 m, find the distance between their tops. Solution: Detailed explanation of exercise 6.5 question 12 is given in the below image and YouTube […]

Triangles | Chapter 6 Exercise 6.5 Question 11:  An aeroplane leaves an airport and flies due north at a speed of 1,000 km per hour. At the same time, another aeroplane leaves the same airport and flies due west at a speed of 1,200 km per hour. How far apart will be the two planes […]

Triangles | Chapter 6 Exercise 6.5 Question 10:  A guy wire attached to a vertical pole of height 18 m is 24 m long and has a stake attached to the other end. How far from the base of the pole should the stake be driven so that the wire will be taut? Solution: Detailed explanation […]

Triangles | Chapter 6 Exercise 6.5 Question 9:  A ladder 10 m long reaches a window 8 m above the ground. Find the distance of the foot of the ladder from base of the wall. Solution: Detailed explanation of exercise 6.5 question 9 is given in the below image and YouTube video. Next Post

Triangles | Chapter 6 Exercise 6.5 Question 8:  In the following figure, O is a point in the interior of a triangle ABC, OD ⊥ BC, OE ⊥ AC and OF ⊥ AB. Show that (i) OA2 + OB2 + OC2 − OD2 − OE2 − OF2 = AF2 + BD2 + CE2 (ii) AF2 + BD2 […]