Go to the basics!
Geometry
Level
pending
Let ABC be a triangle and D be the midpoint of BC.∠ADB = 30° and ∠ACB = 15°. Find the value of ∠ABD.
The answer is 75.
This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try
refreshing the page, (b) enabling javascript if it is disabled on your browser and,
finally, (c)
loading the
non-javascript version of this page
. We're sorry about the hassle.
1 solution
Since ∠ADB = 2∠ACB and BD = DC, D is the circumcentre of ABC. Since angle in semicircle = 90°, ⇒∠ABD+90°+15°=180° ⇒∠ABD = 75°