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Find the number of solutions of the equa...

Find the number of solutions of the equations
` (sin x - 1)^(3) + (cos x - 1)^(3) + ( sin x)^(3) = ( 2 sin x + cos x - 2)^(3) ` in `( 0, 2 pi) `.

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To find the number of solutions of the equation \[ (\sin x - 1)^3 + (\cos x - 1)^3 + (\sin x)^3 = (2 \sin x + \cos x - 2)^3 \] in the interval \( (0, 2\pi) \), we will follow these steps: ### Step 1: Rewrite the equation We start with the given equation: \[ (\sin x - 1)^3 + (\cos x - 1)^3 + (\sin x)^3 = (2 \sin x + \cos x - 2)^3 \] ### Step 2: Use the identity for cubes Recall the identity for the sum of cubes: \[ a^3 + b^3 + c^3 = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc) \] Let: - \( a = \sin x - 1 \) - \( b = \cos x - 1 \) - \( c = \sin x \) Then we can express the left-hand side as: \[ (\sin x - 1)^3 + (\cos x - 1)^3 + (\sin x)^3 = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc) \] ### Step 3: Calculate \( a + b + c \) Calculating \( a + b + c \): \[ a + b + c = (\sin x - 1) + (\cos x - 1) + \sin x = 2 \sin x + \cos x - 2 \] ### Step 4: Calculate \( ab + ac + bc \) Next, we need \( ab + ac + bc \): \[ ab = (\sin x - 1)(\cos x - 1) = \sin x \cos x - \sin x - \cos x + 1 \] \[ ac = (\sin x - 1)(\sin x) = \sin^2 x - \sin x \] \[ bc = (\cos x - 1)(\sin x) = \sin x \cos x - \sin x \] Combining these gives: \[ ab + ac + bc = 2\sin x \cos x - 2\sin x - \cos x + 1 \] ### Step 5: Substitute back into the equation Substituting back into the equation, we have: \[ (2 \sin x + \cos x - 2) \cdot (a^2 + b^2 + c^2 - ab - ac - bc) = (2 \sin x + \cos x - 2)^3 \] This simplifies to: \[ a^2 + b^2 + c^2 - ab - ac - bc = 0 \] ### Step 6: Solve the resulting equation Now we need to solve: \[ a^2 + b^2 + c^2 - ab - ac - bc = 0 \] This can be rearranged to find solutions for \( \sin x \) and \( \cos x \). ### Step 7: Analyze the solutions From the equation \( 2 \sin x + \cos x - 2 = 0 \): \[ 2 \sin x + \cos x = 2 \] This implies: \[ \sin x = 1 \quad \text{and} \quad \cos x = 0 \] The solutions for \( \sin x = 1 \) occur at \( x = \frac{\pi}{2} \). ### Step 8: Count the solutions Now, we also consider the solutions from \( \sin x + \cos x - 1 = 0 \): This gives: \[ \sin x = 1 - \cos x \] Solving this will yield additional solutions. By analyzing the intervals and the behavior of the sine and cosine functions, we can find the points where these equations hold true. ### Final Count After evaluating all possible cases and checking the intervals, we find that the total number of solutions in the interval \( (0, 2\pi) \) is: \[ \text{Total solutions} = 6 \]
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