to solve 2unknowns 2 equations using matrix in TI 89

[zaw]

help me anyone who knows how to solve the 2 unkowns 2 equations using matrix function in TI 89. for example:

xcos60+ycos140=0
xsin60+ysin140=1000

to find the x and y value using Matrix.

[bluesuit]

Enter this. (rref can be gotten by [2nd], [5 (MATH)], [4 (Matrix)], [4 ("rref(")]

rref([[cos(60),cos(140),0][sin(60),sin(140),1000]])

and it'll give you:

[[1, 0, 777.8619][0, 1, 507.7133]]
which means
1x+0y=777.8619
0x+1y=507.7133

Make sure when you enter this, you enter the correct coefficient in the corresponding place every time. You can use this technique for any number of variables. Also note that you might be able to get exact values by using the exact mode.