Question

In the given angle abc is a right angled triangle at c and ad _! Ab . If angle b =40 then find angle bac

Answer 1

Right angled triangle at B altitude is BD AD =3 DC = 9 find AB?

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1 ANSWER



Girija Warrier, Passionate about Maths & Music...

Answered Aug 22, 2017 · Author has 1.9kanswers and 1.6m answer views



Angle B = 90° ( given)

=> <1 + <2 = 90° ( as shown in the figure)……(1)

BD is perpendicular to AC ( given)

=> <1 + <DCB = 90° …….(2)

=> < DCB = <2 ………….by (1) & (2)

& < BAD = <1

So, Triangle BCD ~ triangle ABD ( by AAA similarity theorem)

=> BC/AB = CD/BD = BD/AD ( corresponding sides of similar triangles)

=> BC/AB = 9/BD = BD/3

= BD² = 27

=> BD = 3√3

AB² = AD² + BD²

=> AB² = 3² + (3√3)²

= AB² = 9 + 27 = 36

=> AB = 6

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