Answer:
see explanation
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°
Subtract the sum of the given angles from 180 for B
B = 180° - (90 + 40)° = 180° - 130° = 150°
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sin40° = =
Multiply both sides by 21
21 × sin40° = a, thus
a ≈ 13.5 ( to the nearest tenth )
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cos40° = =
Multiply both sides by 21
21 × cos40° = b, thus
b ≈ 16.1 ( to the nearest tenth )