Find the possible values of angle ##∠ADB##

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SUMMARY

The discussion centers on calculating the angle ∠ADB using the cosine and sine rules. The value of BC is established as 10.25 cm through the cosine rule. The sine rule is applied to find BK as 3 cm, leading to the conclusion that ∠BDK is 48.59°. Consequently, ∠ADB is determined to be 131.4°. An alternative scenario is presented where ∠ADB equals 48.59° if BD is positioned on the opposite side of the perpendicular line.

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chwala
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Homework Statement
See attached ( kindly allow me to post as it is on exam script)
Relevant Equations
Understanding of the Triangle
1686582692210.png


My take:

1686582845878.png


I got ##BC=10.25## cm, using cosine rule...no issue there. For part (b)
##BK=3cm## using sine rule i.e ##\sin 30^0 =\dfrac{BK}{6}##
Thus it follows that ##∠BDK=48.59^0## ...⇒##∠ADB=131.4^0## correct...any other approach?

Also:

##∠ADB=48.59^0## when BD is on the other side of the given perpendiculor line.

cheers guys
 

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Seem ok to me.
'Not to scale' is an understatement....

And instead of outcomes, post steps: ##\angle ADB = \arcsin 3/4 = ...## is so much clearer !

##\LaTeX ## degrees is ^\circ : ##30^\circ##

##\ ##
 
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BvU said:
Seem ok to me.
'Not to scale' is an understatement....

And instead of outcomes, post steps: ##\angle ADB = \arcsin 3/4 = ...## is so much clearer !

##\LaTeX ## degrees is ^\circ : ##30^\circ##

##\ ##
@chwala ,

In case you miss @BvU 's post, it bears repeating... on all counts. :wink:
 
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