Posted by **Shubham** on Thursday, May 22, 2008 at 9:33am.

sin(x)+cos(x)=2/3

find the value of

sin(x)

- Maths -
**Reiny**, Thursday, May 22, 2008 at 10:25am
square both sides

sin^2 x + 2sinxcosx + cos^2 x = 4/9

1 + sin 2x = 4/9

sin 2x = -5/9

2x = 213.75 or 2x = 326.25

x = 106.87º or x = 163.126º

but since we performed a "squaring" operation we have to verify each answer.

when x = 106.87 , sin106.87 + cos106.87 = .66676.., so that works

but for x= 163.126, the result was -.66676 which is NOT the right side

so sinx = sin106.87 = .9569

## Answer This Question

## Related Questions

- TRIG! - Posted by hayden on Monday, February 23, 2009 at 4:05pm. sin^6 x + cos^6...
- tigonometry - expres the following as sums and differences of sines or cosines ...
- Mathematics - Trigonometric Identities - Let y represent theta Prove: 1 + 1/tan^...
- algebra - Can someone please help me do this problem? That would be great! ...
- Calculus 12th grade (double check my work please) - 1.)Find dy/dx when y= Ln (...
- trig - Reduce the following to the sine or cosine of one angle: (i) sin145*cos75...
- Math - Calculus - The identity below is significant because it relates 3 ...
- Trig - Find sin(s+t) and (s-t) if cos(s)= 1/5 and sin(t) = 3/5 and s and t are ...
- Trig - Given: cos u = 3/5; 0 < u < pi/2 cos v = 5/13; 3pi/2 < v < ...
- Trigonometry - Solve the equation for solutions in the interval 0<=theta<...

More Related Questions