calling tbhe angle A,B,C as usual in a diagram, use the law of sines to find that
sin(∠BDC)/5 = sin(30)/4
so, sin ∠BDC = 5/8
But you want the obtuse angle.
Now you know that ∠BDA = 180 - ∠BDC
And, since triangle BDA is isosceles, ∠DAB = ∠BDA
Now you can find ∠B, and use the law of sines to find the other sides.
And recall that in any triangle ABC, the area = 1/2 ab sinC
triangular flower garden ABC in which AB = 4m, BC = 5and ∠BCA =30. Point D lies on AC such that BD = 4 m and ∠BDC is obtuse.
Find:
(a) ∠BDC
(b) the length of AD
(c) the length of DC
(d) the area of the flower garden ABC
1 answer
1 answer