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Forum URL: http://www.cut-the-knot.org/cgi-bin/dcforum/forumctk.cgi
Forum Name: College math
Topic ID: 77
#0, trigonometry - compound angles
Posted by fivepoint9 on Mar-14-01 at 01:27 AM
a hole in a block of metal that is lying flat on a table has 2 angles given:

angle A is in the xz plane dimentioned from the verticle
angle B is in the yz plane dimentioned from the verticle

to find angle C which is the angle in the xy plane from the verticle the formula is tan(c)=(1/tan(b))*tan(a)

to find the cross section angle which is an angle u would get if u were to saw cut the block of steel through the hole at angle C in the xy plane and view the resulting part from the side perpendicular to the cut. the formula for this angle is

tan(D)=sqrt((tan(A)^2)+(tan(B)^2))

the question is: If I rotate the block of steel 30deg ccw in the yz plane what will be the formulas for angle A, C, D. when B=B+30.

any help will be greatly appreciated.