Bdmo past problems


Can anyone of you give me some outline of this problem?

try some trignometry and you would get some value of angle A

Can you please do the complete solution? How can we use trigonometry here?

Since AB=CD and BC=BC we can consider Sine rule on triangle ABC and Triangle BCD ,
and solving the trigonometric equation we will be done.You will get something like this,
cos(6a)cos(a)=sin(5a)sin(4a) (setting angle A=4a)

Please Give the complete proof. I have noticed the similar triangles But how can I determine the angles.

You have to trig bash. You can do it in many times.
.

I could not do that. Please post the solution.

From LOS we have
sin(4a)cos(6a)= cos(2a)sin(6a)
But solving this a= 45.which is not correct.

Edit: I got a synthetic solution btw.Then again post your solution.

there will be another solution a=10 consider this .

you have used wrong stuff cos6acosa=sin5asin4a will be correct