The value of x is 6.
What are complementary?
Complementary angles are angles that sum up to 90°.
Analysis:
For angles A and B, to be complementary, the sine of angle A must be equal to the cosine of angle B.
sin A = cos B
5X+9 = 3x+21
5x - 3x = 21 - 9
2x = 12
x = 6
In conclusion, the value of x to make angles A and B complementary is 6.
Learn more about complementary angles: brainly.com/question/98924
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