Problems involving general triangles (1 Viewer)

[kpad5991]

Let ABC be a triangle and let D be the midpoint of AC. Let BD = m and angle ADB = theta. AC = b, AB = c and BC = a. Show that a^2 + c^2 = 2m^2 + 0.5b^2

 

[dan964]

Let ABC be a triangle and let D be the midpoint of AC. Let BD = m and angle ADB = theta. AC = b, AB = c and BC = a. Show that a^2 + c^2 = 2m^2 + 0.5b^2

you might need to draw a diagram first; and split the two triangles into triangle ABD and BCD, and use cosine rule on each for a^2 and c^2, and add the two together (the two cosine terms cancel) I won't put my working but that is the reasoning.