well!! this is how u do the question !!

Draw a random triangle (when i mean random i mean not a right-angled triangle)

label the edges A, B, C !!

Then put the angle in !!

Now for the area of a triangle to work u must have a SAS (Side - angle-side) meaning a angle between two sides !!

You can see that u dont have that, so use the sine rule to work out BAC and from that do 180 minus (your worked out angle + 110) this will give you the angle ACB !!

Then you can sub in the values into 0.5 x a x b x sinC

Now to show you what i mean !!!

Now above is a diagram i drew to help u visualize this !!! (P.S i hope u can see this !!!)

Now we have to work out BAC or in other words **X ** !!

So you use the sine rule :

sin x = (5.7xsin110 ) / 8.6

x = Sin^-1 (ANS = 38.5 to 3 sig figs (keep the value on your calculator!!)

Now we have to work out BCA or angle **Y** !!

To do this you do the following:

y =180 - (your answer on your calculator + 110)====> angles in a triangle equal 180 degrees

y = 31.5 degrees to 3 sig figs (again keep your calculator answer on your calculator !!)

Finally you can work out the area by subbing in angle **Y**, n the two other sides into the equation :

0.5 x a x b x sinC

so this is how it is::

0.5 x 8.6 x 5.7 x sin (your calculator answer for BCA) = 12.79829599

= 12.8cm^2 (3 sig figs !!!)

I think this is right and i hope i have helped !!

Answered Tue 12th June, 2012 @ 20:05 by

BraniacEdited by

Braniac on Tue 12th June, 2012 @ 20:17