Question

If a+b=90° and a =2b find cos²a+sin²b

Answer 1

a+b=90°...(1)

a=2b...(2)

using eq2 in eq1

we get

2b+b=90

3b=90

b=30°

use value of b in eq2

we get

a=60°

now,

cos^2a+sin^2b

cos^260°+sin^230°

1/2^2+1/2^2

1/4+1/4

2/4

1/2 is the answer

Answer 2

Answer:

a=2b.....1

a+b=90

3b=90(from1)

b=30

=>a=60

cos²a+sin²b=cos²60+sin²30

=(1/2)²+(1/2)²

=1/4 + 1/4

=1/2

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