The sine value of the supplementary angle in junior high school is equal. According to the relevant information, there is a sine theorem in the chapter of junior high school mathematics, which includes the sine value of complementary angle is equal, so the sine value of complementary angle is equal in junior high school. The two complementary angles add up to 180, which is explained in the chapter of acute trigonometric function in the ninth grade super class. The sine values of complementary angles are equal, and complementary angles are not equal to ∠ a+∠A+∠B = 90°, and sin ∠ a = cos ∠ b.