Problem:
In the adjoining figure of a rectangular solid, β DHG=45β and β FHB=60β. Find the cosine of β BHD.
Answer Choices:
A. 63ββ
B. 62ββ
C. 36ββ
D. 46ββ
E. 46ββ2ββ
Solution:
Without loss of generality, let HF=1 in the adjoining figure. Then BH=2,
BF=3β=DG=GH, and DH=6β
Since DC=HC=3β,β³DCBβ
β³HCB and DB=HB=2. Since β³DBH is isoceles,
cosΞΈ=221β6ββ=46ββ
.jpg)
.jpg)