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Trignometry

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27 Apr 2009 10:28:07 IST

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IMPORTANT QUESTION : let ABC be a right angled triangle with BC =3 and AC=4. Let D be a point on the

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IMPORTANT QUESTION : let ABC be a right angled triangle with BC =3 and AC=4. Let D be a point on the hypotenuse AB such that angle BCD=30 degree. Write the length of 'CD'

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VARUN (aryan)

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27 Apr 2009 11:39:04 IST

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any1

Marshall Eriksen

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27 Apr 2009 16:05:28 IST

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See, Draw The Triangle ABC and find its angles, ull find that they are 53.13 36.86 and 90 degrees....vertex B with 53.13 degree angle...now if u consider triangle BCD, u know B is 53.13 u knw BCD is 30 degree and the third angle will be 180 - other two....now u can use sine rule or cos rule to find length CD

debmalya choudhuri

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27 Apr 2009 22:20:49 IST

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i just have a question are u provided with claculators and tables stuff in itt or olmpaids i guess no so try solving in any other way plzz

prachi

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27 Apr 2009 22:26:54 IST

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ans is sq.rot 3 x1.5=2.58

Deepak

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29 Apr 2009 08:40:39 IST

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in tri ABC

sinB = 4/5

now in triBCD

3/ sin30^o = CD / sinB => CD = 24/5 sine law

VARUN (aryan)

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29 Apr 2009 09:29:03 IST

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but answer to this question is 24/3+4*1.73

VARUN (aryan)

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29 Apr 2009 09:29:20 IST

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1.73 i mean under the root 3

VARUN (aryan)

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29 Apr 2009 09:32:50 IST

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any plzz solve it

NugoRama

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29 Apr 2009 09:50:35 IST

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sin@1 = 4/5 , cos@1= 3/5

now @2 = 180 - 30 - @1

sin@2= sin( 180 - 30 - @1)

=sin(30 + @1)

=sin30cos@1 + cos30sin@1

=1/2x3/5 + root3/2x4/5

=3/10 +4root3 /10

= (3 + 4root3)/10

now applying lami's theorem in triangle BCD.

sin@2/BC = sin@1 /CD

sin@2 x CD = sin@1 x BC

(3 + 4root3)/10 x CD = 4/5 x 3

CD = 24/(3 + 4root3) .......answer

Deepak

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29 Apr 2009 23:03:01 IST

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CD = 3 sinB/sin(60 + A)

=> CD = 24/ (3 + 4sqrt3)

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