Homework Help: Trig Math

Posted by Jane on Monday, March 29, 2010 at 9:27pm.

I need help with this problem. I don't get how to do it or how they got that answer.
A force of 50 pounds acts on an object at an angle of 45 degrees. A second force of 75 pounds acts on the object at an angle of -30 degrees. What was the direction and the magnitude of the resultant force?

The answer is |F|≈ 100.33 lb and Ө ≈ -1.22 degress

Trig Math - Reiny, Monday, March 29, 2010 at 10:51pm
From the origin on the x-axis draw a line at 45 degrees with length 50
From the origin draw a line 30 degrees down into the fourth quadrant with length 75

So the angle between the two forces is 75 degrees.
Complete the parallelogram and draw the diagonal.
That diagonal is the resultant force F

I see a triangle with sides 50 and 75 and an angle of 105 degrees between them. ... (180-75)

By Cosine Law
|F|^2 = 50^2 + 75^2 - 2(50)(75)cos 105
= 10066.1428
|F| = 100.33

Now by Sine Law
SinŲ/75 = sin 105/100.33
sinŲ = .72206
Ų = 46.225

so subtracting the 45 from that leaves us with Ų = 1.225 below the x-axis or -1.225 degrees

Answer this Question

Related Questions

math - I've got a problem i need help on i need to find the proper ...
math - I've got a problem i need help on. i've got to use digits and ...
Trig - I have no idea how to do this problem From an airplane flying 2 ...
math - i've got a problem i need help on its 52 * 7 = 7m i need to know ...
Trigonometry - Use the trig Identities to find the other 5 trig functions. ...
math exponents - i need to write each expression as a product of the same factor...
MATH - i need to write each expression as a product of the same factor: * = ...
calculus-integration! - should i use substitution?? if yes how should should i ...
Math - When I did the following problem, I got -12 as my answer. It is an ...
Math 141 - I am having trouble with this problem. perform the indicated ...

For Further Reading

First Name:
School Subject:
Answer: