Sin (30 + a) = - 4 / 5, then cos (A-60)=

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• 1. sin(a+30°)+cos(a+60°)2cosa=______ ．
• 2. Sin (a + 30 degrees) - cos (a + 60 degrees) / 2sina=
• 3. Given sin α = 12 / 13, α ∈ (π of 0,2), cos β = - 4 / 5, β ∈ (π of 2), find cos (α - β), sin (α - β)
• 4. Simplify cos (α + 30 °) cos (α - 30 °) - sin (α + 30 °) sin (α + 150 °), Simplify cos (α + 30 °) cos (α - 30 °) - sin (α + 30 °) sin (α + 150 °),
• 5. By simplifying sin (α + 30 °) + sin (30 ° - α) cos α___ ．
• 6. Simplifying sin ^ 2 A + cos a * cos (60 + a) - Sin ^ (30-a)=
• 7. An acute angle trigonometric function problem If the adjacent sides of the parallelogram are 10 meters and 15 meters long respectively, and their included angle is 60 degrees, then the area of the parallelogram is?
• 8. The problem of two simple trigonometric functions with acute angles Given that angles a and B are the two acute angles of RT triangle ABC, Sina and CoSb are the two roots of the square of equation 2 (x) - MX + 1 = 0, then how many degrees is angle a = and how many is angle m? Given that angle a is an acute angle, Tana = root 3, then sin (1 / 2) a =?
• 9. Calculation of trigonometric function of acute angle In this lesson, I didn't come. The teacher left my homework. I'll go to class later. 1. Calculate the sine, cosine and tangent of the two acute angles in the following right triangle. 2. In RT △ ABC, if the length of each side is doubled, what's the change of the sine, cosine and tangent of the acute angle a? 3. As shown in the figure, in RT △ ABC, angle c = 90 °, AC = 8, Tana = 3 / 4, calculate the value of sina and CoSb If I can't send the pictures of question 1 and question 3, just answer the answers of question 2
• 10. Acute trigonometric function 1. Simplification: | sin40 ° - 1 | + √ (1-cos ^ 240 °) 2. Assume 0 degree
• 11. (3y-6)(-y) (-3x)(4x²-4/3x+1) (-xy)(2x-5y-1) 5x(2x+3)+x(x+1) 2z(a² +3a-2)-2(a³+2a&sup The title of the book （3y-6)(-y) (-3x)(4x²-4/3x+1) (-xy)(2x-5y-1) 5x(2x+3)+x(x-1) 2a(a² +3a-2)-2(a³+2a²-a+1）
• 12. How to decompose 3A & sup2-12a + 12 = 0
• 13. To simplify the evaluation, we know | 2a-b + 1 | + (3a + 3 / 2 b) & sup2; = 0, find the algebraic formula B & sup2 / / A + B △ A / a-b - 1) x (a - A & sup2 / / a) Note: B & sup2 / A + B is the square of a + B Find the value of the Algebra B & sup2; / (a + b) / {A / (a-b) - 1} x {a - A & sup2; / (a + b)}
• 14. Given that 2a-3b + C = 0, 3a-2b-6c = 0, find the value of a & sup2; + B & sup2; + C & sup2; / 2A & sup2; + B & sup2; - C & sup2
• 15. （a+b/a-b）² * 2a-2b/3a+3b - a²/a²-b² ÷ a/b
• 16. In △ ABC, given ∠ a = 60 & ordm;, ∠ B ∶ C = 1 ∶ 5, find the degree of ∠ B
• 17. Given the degree ratio of the five outer angles of the Pentagon is 1:2:3:4:5, find the degree of the five inner angles of the Pentagon
• 18. In the triangle ABC, the angle a-angle B = 60 ° and the angle B-angle C = 15 ° are used to find the degree of ∠ a ∠ B ∠ C
• 19. In △ ABC, ∠ a - ∠ B = ∠ B - ∠ C = 15 °, find the degree of ∠ a ∠ B ∠ C
• 20. It is known that in △ ABC, ∠ B is 20 ° larger than ∠ a, and ∠ B is 20 ° smaller than ∠ C. The degree of three internal angles in △ ABC can be calculated