Question

If a + B = 90° and a = 2B then cos a +sin' B= ...
A)-1/2
B)
-1
C) 2
D) 1/2​

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

Hope it's useful.

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