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# Rearrange A= 1/2 absinC ? watch

1. I'm given a triangle, there are 2 known sides and I have to find the included angle

I've labelled the angle as "C" and the known sides as "a" and "b"

I am given the area [scroll to bottom of post to see values]

I was wondering if there is a way to rearrange the formula of A= 1/2absinC so I could work out what "C" is. I've tried this but no lucl :'(

Is there another way to work out this question??

thanks^^

a = 13cm
b = 11cm

Area = 67.2cm (squared)
Show that angle C = 70.0 degrees
2. yes, you can rearrange it...
multiply both sides by 2
then divide both by ab
you should then have an expression for sin C, use your calulator's sin^-1 function to work out C.
3. (Original post by Freeze123)
I'm given a triangle, there are 2 known sides and I have to find the included angle

I've labelled the angle as "C" and the known sides as "a" and "b"

I am given the area [scroll to bottom of post to see values]

I was wondering if there is a way to rearrange the formula of A= 1/2absinC so I could work out what "C" is. I've tried this but no lucl :'(

Is there another way to work out this question??

thanks^^

a = 13cm
b = 11cm

Area = 67.2cm (squared)
Show that angle C = 70.0 degrees
You could make sin*C the subject, but it is often easier to simply insert the values in the correct locations and then solve.

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