Register to reply 
Geometry problem (angle of body diagonal of a cube) 
Share this thread: 
#1
Jan1314, 08:21 AM

P: 314

refer to the following image
so consider the angle of the yellow theta on the top left. this is 45*. if we fix one side of both red lines at the blue circles, and we slide the other end along the green side of the cube, ie just think of the green lines as rails for the red lines to slide along. then this will extend the lateral length of the lines as the length in the zdirection (up and down) remains constant. shouldn't this then DECREASE the angle specified in the picture not increase it? i'm asking because i've been asked to solve for this angle and θ<45* is not what i got. I got the angle to be 70* which is not intuitive. i am asking for intuition on this problem as opposed to an involved analytical method of solving for that angle. i've already done it analytically i just have no idea why that angle increases and doesn't decrease. thanks all 


#2
Jan1314, 08:42 AM

P: 12

I believe the first angle is 90°, not 45° as you originally thought. Thus the angles does indeed decrease to 70.5°



#3
Jan1314, 12:37 PM

P: 314

Ahaha... I made another stupid mistake... Thanks



Register to reply 
Related Discussions  
Moving body on a diagonal path  Introductory Physics Homework  3  
2body problem  how to get the angle theta?  Introductory Physics Homework  6  
Moment of inertia for a hollow cube. Rotating about diagonal opp corners  Classical Physics  5  
Express the edge length of a cube as a function of the cubes diagonal  Calculus & Beyond Homework  6  
2Body inverse cube problem  Introductory Physics Homework  0 