We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive pseudonymised information about your use of our website.
Please click on "Accept cookies" if you agree to the setting of cookies. Cookies that do not require consent remain unaffected by this, see
cookie policy and privacy policy.
DECLINE COOKIES

so:

Cos(x) = 7^2 + 10^2 - 10^2/2(7 * 10)

cos(x) = 49/140

acos(0.35) = x

x= 69.5 degrees.

Let me know if this looks good for explaining my answer!

Thanks

StarStrike Feb 14, 2019

#1**+1 **

You kinda' have the right idea, StarStrike

Note...BA = CA = 10 m

The Law of Cosines says that

BC^2 = BA^2 + CA^2 - 2(BA)(CA) cos (x) .....so we have...

7^2 = 10^2 + 10^2 - 2(10)(10) cos (x) simplify

49 = 200 - 200 cos(x) subtract 200 from both sides

[ 49 - 200] = - 200 cos(x) divide both sides by - 200

[ 49 - 200 ] / -200 = cos (x)

To find the measure of x, use the arccos (inverse cosine)...make sure you are in "degree" mode...so we have

arccos [ ( 49 - 200) / -200 ] = x = 40.97°

CPhill Feb 14, 2019