Re: newbies need sum help..

For the first problem you've left out some critical data - such as the speed of the two boats - so it's impossible to answer as written.

For the 2nd you know that the 3 sides of the triangle are lengths 7, 8, and 9 - do you see what that is? Now apply the law of cosines:

$\displaystyle C^2 = A^2 + B^2 - 2AB \cos(c)$

You have values for A, B and C, so solve for $\displaystyle \cos(c) $ and hence the angle 'c'. Repeat for angle 'b', and angle 'a' is 180 degrees - c - b.

Re: newbies need sum help..

For the 2nd you know that the 3 sides of the triangle are lengths 7, 8, and 9 - do you see what that is? Now apply the law of cosines: $\displaystyle C^2 = A^2 + B^2 - 2AB \cos(c)$ You have values for A, B and C, so solve for $\displaystyle \cos(c) $ and hence the angle 'c'. Repeat for angle 'b', and angle 'a' is 180 degrees - c - b.[/QUOTE] CanU please figure it out .. how it the 3 sides became 7,8,9 ?? can u give the figure?

Re: newbies need sum help..

Quote:

Originally Posted by

**ebaines** For the first problem you've left out some critical data - such as the speed of the two boats - so it's impossible to answer as written.

For the 2nd you know that the 3 sides of the triangle are lengths 7, 8, and 9 - do you see what that is? Now apply the law of cosines:

$\displaystyle C^2 = A^2 + B^2 - 2AB \cos(c)$

You have values for A, B and C, so solve for $\displaystyle \cos(c) $ and hence the angle 'c'. Repeat for angle 'b', and angle 'a' is 180 degrees - c - b.

Two ships leave a dock at the same time. One sails northeast at the rate 8.5 km/hr. The other sails north at a rate 10 km./hr. how far APART are they at the end of two hours.

Re: newbies need sum help..

Quote:

Originally Posted by

**jhaycianofficial** Two ships leave a dock at the same time. One sails northeast at the rate 8.5 km/hr. The other sails north at a rate 10 km./hr. how far APART are they at the end of two hours.

oh im so sorry ..the preceding exercise is THAT !

Re: newbies need sum help..

Quote:

Originally Posted by

**jhaycianofficial** CanU please figure it out .. how it the 3 sides became 7,8,9 ?? can u give the figure?

If you draw two circles that are tangent to each other (the circles are just touching) you can see that the distance between the centers of the two circles is equal to the sum of their radii.