Trigonometry Examples

${(\sin (θ) - \cos (θ))}^{2} + {(\sin (θ) + \cos (θ))}^{2}$

Step 1

Simplify each term.

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Step 1.1

Rewrite ${(\sin (θ) - \cos (θ))}^{2}$ as $(\sin (θ) - \cos (θ)) (\sin (θ) - \cos (θ))$ .

$(\sin (θ) - \cos (θ)) (\sin (θ) - \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.2

Expand $(\sin (θ) - \cos (θ)) (\sin (θ) - \cos (θ))$ using the FOIL Method.

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Step 1.2.1

Apply the distributive property.

$\sin (θ) (\sin (θ) - \cos (θ)) - \cos (θ) (\sin (θ) - \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.2.2

Apply the distributive property.

$\sin (θ) \sin (θ) + \sin (θ) (- \cos (θ)) - \cos (θ) (\sin (θ) - \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.2.3

Apply the distributive property.

$\sin (θ) \sin (θ) + \sin (θ) (- \cos (θ)) - \cos (θ) \sin (θ) - \cos (θ) (- \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3

Simplify and combine like terms.

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Step 1.3.1

Simplify each term.

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Step 1.3.1.1

Multiply $\sin (θ) \sin (θ)$ .

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Step 1.3.1.1.1

Raise $\sin (θ)$ to the power of $1$ .

$\sin^{1} (θ) \sin (θ) + \sin (θ) (- \cos (θ)) - \cos (θ) \sin (θ) - \cos (θ) (- \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.1.2

Raise $\sin (θ)$ to the power of $1$ .

$\sin^{1} (θ) \sin^{1} (θ) + \sin (θ) (- \cos (θ)) - \cos (θ) \sin (θ) - \cos (θ) (- \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.1.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

${\sin (θ)}^{1 + 1} + \sin (θ) (- \cos (θ)) - \cos (θ) \sin (θ) - \cos (θ) (- \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.1.4

Add $1$ and $1$ .

$\sin^{2} (θ) + \sin (θ) (- \cos (θ)) - \cos (θ) \sin (θ) - \cos (θ) (- \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.2

Rewrite using the commutative property of multiplication.

$\sin^{2} (θ) - \sin (θ) \cos (θ) - \cos (θ) \sin (θ) - \cos (θ) (- \cos (θ)) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.3

Multiply $- \cos (θ) (- \cos (θ))$ .

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Step 1.3.1.3.1

Multiply $- 1$ by $- 1$ .

$\sin^{2} (θ) - \sin (θ) \cos (θ) - \cos (θ) \sin (θ) + 1 \cos (θ) \cos (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.3.2

Multiply $\cos (θ)$ by $1$ .

$\sin^{2} (θ) - \sin (θ) \cos (θ) - \cos (θ) \sin (θ) + \cos (θ) \cos (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.3.3

Raise $\cos (θ)$ to the power of $1$ .

$\sin^{2} (θ) - \sin (θ) \cos (θ) - \cos (θ) \sin (θ) + \cos^{1} (θ) \cos (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.3.4

Raise $\cos (θ)$ to the power of $1$ .

$\sin^{2} (θ) - \sin (θ) \cos (θ) - \cos (θ) \sin (θ) + \cos^{1} (θ) \cos^{1} (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.3.5

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$\sin^{2} (θ) - \sin (θ) \cos (θ) - \cos (θ) \sin (θ) + {\cos (θ)}^{1 + 1} + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.1.3.6

Add $1$ and $1$ .

$\sin^{2} (θ) - \sin (θ) \cos (θ) - \cos (θ) \sin (θ) + \cos^{2} (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.2

Reorder the factors of $- \sin (θ) \cos (θ)$ .

$\sin^{2} (θ) - \cos (θ) \sin (θ) - \cos (θ) \sin (θ) + \cos^{2} (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.3.3

Subtract $\cos (θ) \sin (θ)$ from $- \cos (θ) \sin (θ)$ .

$\sin^{2} (θ) - 2 \cos (θ) \sin (θ) + \cos^{2} (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.4

Move $\cos^{2} (θ)$ .

$\sin^{2} (θ) + \cos^{2} (θ) - 2 \cos (θ) \sin (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.5

Apply pythagorean identity.

$1 - 2 \cos (θ) \sin (θ) + {(\sin (θ) + \cos (θ))}^{2}$

Step 1.6

Rewrite ${(\sin (θ) + \cos (θ))}^{2}$ as $(\sin (θ) + \cos (θ)) (\sin (θ) + \cos (θ))$ .

$1 - 2 \cos (θ) \sin (θ) + (\sin (θ) + \cos (θ)) (\sin (θ) + \cos (θ))$

Step 1.7

Expand $(\sin (θ) + \cos (θ)) (\sin (θ) + \cos (θ))$ using the FOIL Method.

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Step 1.7.1

Apply the distributive property.

$1 - 2 \cos (θ) \sin (θ) + \sin (θ) (\sin (θ) + \cos (θ)) + \cos (θ) (\sin (θ) + \cos (θ))$

Step 1.7.2

Apply the distributive property.

$1 - 2 \cos (θ) \sin (θ) + \sin (θ) \sin (θ) + \sin (θ) \cos (θ) + \cos (θ) (\sin (θ) + \cos (θ))$

Step 1.7.3

Apply the distributive property.

$1 - 2 \cos (θ) \sin (θ) + \sin (θ) \sin (θ) + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + \cos (θ) \cos (θ)$

Step 1.8

Simplify and combine like terms.

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Step 1.8.1

Simplify each term.

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Step 1.8.1.1

Multiply $\sin (θ) \sin (θ)$ .

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Step 1.8.1.1.1

Raise $\sin (θ)$ to the power of $1$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{1} (θ) \sin (θ) + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + \cos (θ) \cos (θ)$

Step 1.8.1.1.2

Raise $\sin (θ)$ to the power of $1$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{1} (θ) \sin^{1} (θ) + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + \cos (θ) \cos (θ)$

Step 1.8.1.1.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$1 - 2 \cos (θ) \sin (θ) + {\sin (θ)}^{1 + 1} + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + \cos (θ) \cos (θ)$

Step 1.8.1.1.4

Add $1$ and $1$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{2} (θ) + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + \cos (θ) \cos (θ)$

Step 1.8.1.2

Multiply $\cos (θ) \cos (θ)$ .

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Step 1.8.1.2.1

Raise $\cos (θ)$ to the power of $1$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{2} (θ) + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + \cos^{1} (θ) \cos (θ)$

Step 1.8.1.2.2

Raise $\cos (θ)$ to the power of $1$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{2} (θ) + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + \cos^{1} (θ) \cos^{1} (θ)$

Step 1.8.1.2.3

Use the power rule $a^{m} a^{n} = a^{m + n}$ to combine exponents.

$1 - 2 \cos (θ) \sin (θ) + \sin^{2} (θ) + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + {\cos (θ)}^{1 + 1}$

Step 1.8.1.2.4

Add $1$ and $1$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{2} (θ) + \sin (θ) \cos (θ) + \cos (θ) \sin (θ) + \cos^{2} (θ)$

Step 1.8.2

Reorder the factors of $\sin (θ) \cos (θ)$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{2} (θ) + \cos (θ) \sin (θ) + \cos (θ) \sin (θ) + \cos^{2} (θ)$

Step 1.8.3

Add $\cos (θ) \sin (θ)$ and $\cos (θ) \sin (θ)$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{2} (θ) + 2 \cos (θ) \sin (θ) + \cos^{2} (θ)$

Step 1.9

Move $\cos^{2} (θ)$ .

$1 - 2 \cos (θ) \sin (θ) + \sin^{2} (θ) + \cos^{2} (θ) + 2 \cos (θ) \sin (θ)$

Step 1.10

Apply pythagorean identity.

$1 - 2 \cos (θ) \sin (θ) + 1 + 2 \cos (θ) \sin (θ)$

Step 1.11

Simplify each term.

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Step 1.11.1

Reorder $2 \cos (θ)$ and $\sin (θ)$ .

$1 - 2 \cos (θ) \sin (θ) + 1 + \sin (θ) (2 \cos (θ))$

Step 1.11.2

Reorder $\sin (θ)$ and $2$ .

$1 - 2 \cos (θ) \sin (θ) + 1 + 2 \cdot \sin (θ) \cos (θ)$

Step 1.11.3

Apply the sine double-angle identity.

$1 - 2 \cos (θ) \sin (θ) + 1 + \sin (2 θ)$

Step 2

Add $1$ and $1$ .

$- 2 \cos (θ) \sin (θ) + 2 + \sin (2 θ)$