In the triangle ABC, the opposite sides of the angles a, B and C are a, B and C respectively, and a + C / 18 = B-A / 7, C-B / C-A = 1 / 8 is used to find sinatan B

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• 1. Given that a, B and C are the lengths of the three sides of △ ABC and satisfy A2 + 2B2 + c2-2b (a + C) = 0, then the shape of the triangle is______ ．
• 2. In △ ABC, it is known that a, B and C are the side lengths corresponding to three inner angles a, B and C respectively, and B & # 178; + C & # 178; - A & # 178; = BC (1) Find the size of angle A (2) If B = 1 and the area of △ ABC is 3 √ 3 / 4, find the length of side C
• 3. It is known that a + B + C = 0, ABC = 8, the square of a + the square of B + the square of C = 32 Connect Find one of a + one of B + one of C We need to be quick
• 4. If a, B and C satisfy a + B + C = 0 and ABC = 8, then the value of 1 / A + 1 / B + 1 / C is () A positive number B negative C zero D nonzero rational number
• 5. Given that a + B + C = 0 and ABC is not equal to 0, calculate the value of a {1 / B + 1 / C} + B {1 / C + 1 / a} + C {1 / A + 1 / b} + 3,
• 6. Given | a | = 1, | B | = 2, | C | = 3, and a > b > C, find the value of ABC
• 7. Let a, B, C be the three sides of the triangle ABC, and satisfy (1) a > b > C; (2) 2B = a + C; (3) A2 + B2 + C2 = 84, then the integer B=______ ．
• 8. If the three sides of △ ABC a, B, C satisfy a + B = 10, ab = 18, C = 8, try to judge the shape of △ ABC
• 9. The lengths of three sides of △ ABC are a, B, C respectively, and a > b > C, a, B, C are all positive integers. If the condition 1 / A + 1 / B + 1 / C = 1 is satisfied, the existence of △ ABC can be judged
• 10. In △ ABC, the lengths of three sides are positive integers a, B and C respectively, and B ≥ A. if B = 4 and C = 6, how many triangles are there
• 11. In △ ABC, if A2 + B2 = 25, A2-B2 = 7, C = 5, then the height of the largest edge is______ ．
• 12. In △ ABC, if A2 + B2 = 25, A2-B2 = 7, C = 5, then the height of the largest edge is______ ．
• 13. 2013 China Normal University self recruitment question 2 ·· proving A2 + B2 + C2 + D2 = 9r2 I feel ashamed to die in the second question··
• 14. If A2 + B2 + c2-ab-3b-2c + 4 = 0, then the value of a + B + C is______ ．
• 15. It is known that a and B belong to (0, positive infinity), and 2C > A + B
• 16. In △ ABC, note that a, B and C are opposite sides of a, B and C respectively, and S is the area of triangle, and prove that C ^ 2-A ^ 2-B ^ 2 + 4AB ≥ 4 √ 3S This is the 19th question of the test paper. It's not very difficult, but I haven't thought about it for a long time. Please help me solve it~ PS: because the characters are not standard, I'll use words to explain it again. Verification: the square of C minus the square of a minus the square of B plus 4AB is greater than or equal to 4 times the root sign 3 times s~
• 17. In the triangle ABC, we know that 2sinbxcosc = Sina, a = 120 degrees, a = 1, and find the area of B and triangle ABC
• 18. In the triangle ABC, if a is known to be an acute angle and B = 3asinb, then Tana=
• 19. Let a, B, C opposite the three interior angles of △ ABC, if its area s = C ^ 2 - (a-b) ^ 2, then Tan (C / 2) =?
• 20. In △ ABC, 2b = a + C, B & # 178; = AC, then △ ABC must be () A. Acute triangle B, obtuse triangle C, isosceles triangle D, equilateral triangle The scope is the five required exercises of sine theorem and cosine theorem in mathematics,