Question

sin²A + cos²A = 1 (How?)​

Answer 1

Answer:

it is formula dr one..........

Step-by-step explanation:

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Answer 2

Let's consider a right angle triangle having sides a ,b , c

then

$\sin( \theta) \: = \frac{b}{c} \\ \\ \cos(\theta) \: = \frac{a}{c} \\ \\ { \sin}^{2} \theta \: + {\cos}^{2} \theta \: = \frac{ {b}^{2} }{ {c}^{2} } + \frac{ {a}^{2} }{ {c}^{2} } \\ \\ = \frac{ {b}^{2} + {a}^{2} }{ {c}^{2} } \: \: \: \: .....(1)$

also according to Pythagoras theorem

${b}^{2} + {a}^{2} \: = \: {c}^{2}$

we can rewrite the formula as

$\\ \frac{ {b}^{2} + {a}^{2} } { {c}^{2} } = \: 1 \: \: \: \: ......(2)$

Compare equation (1) and equation (2)

$\sin^{2} \theta + \cos^{2} \theta \: = 1$

that's all !!