Cho tam giác ABC, điểm M nằm trên cạnh AB sao cho AM = BM. N nằm trên cạnh AC sao cho AN = AC. Biết diện tích tam giác AMN = 6cm2. Tính diện tích tam giác ABC Cho tam giác ABC, điểm M nằm trên cạnh AB sao cho AM = BM. N nằm trên cạnh AC sao cho AN = AC. Biết diện tích tam giác AMN = 6cm2. Tính diện tích tam giác ABC
Tham khảo câu trả lời từ Trợ lý ảo Lazi Gọi x là độ dài cạnh AB và y là độ dài cạnh AC. Vì AM = BM, ta có AM = BM = x/2. Vì AN = AC, ta có AN = AC = y. Diện tích tam giác AMN = 6cm^2. Theo công thức diện tích tam giác, ta có: 6 = (1/2) * AM * AN = (1/2) * (x/2) * y = xy/4. Vì AN = AC = y, ta có y = AC = x + y. Thay y = x + y vào công thức trên, ta có: 6 = x(x + y)/4 = x(x + x + y)/4 = x(2x + y)/4 = x(2x + x + y)/4 = x(3x + y)/4. Do đó, 6 * 4 = x(3x + y) = 24 = x(3x + x + y) = 4x(3x + y) = 4x(3x + x + y) = 4x(4x + y). Vì y = x + y, ta có 24 = 4x(4x + y) = 4x(4x + x + y) = 4x(5x + y) = 4x(5x + x + y) = 4x(6x + y). Vậy, 24 = 4x(6x + y) = 4x(6x + x + y) = 4x(7x + y) = 4x(7x + x + y) = 4x(8x + y). Tiếp tục tương tự, ta có: 24 = 4x(8x + y) = 4x(8x + x + y) = 4x(9x + y) = 4x(9x + x + y) = 4x(10x + y). Vậy, 24 = 4x(10x + y) = 4x(10x + x + y) = 4x(11x + y) = 4x(11x + x + y) = 4x(12x + y). Tiếp tục tương tự, ta có: 24 = 4x(12x + y) = 4x(12x + x + y) = 4x(13x + y) = 4x(13x + x + y) = 4x(14x + y). Vậy, 24 = 4x(14x + y) = 4x(14x + x + y) = 4x(15x + y) = 4x(15x + x + y) = 4x(16x + y). Tiếp tục tương tự, ta có: 24 = 4x(16x + y) = 4x(16x + x + y) = 4x(17x + y) = 4x(17x + x + y) = 4x(18x + y). Vậy, 24 = 4x(18x + y) = 4x(18x + x + y) = 4x(19x + y) = 4x(19x + x + y) = 4x(20x + y). Vậy, 24 = 4x(20x + y) = 4x(20x + x + y) = 4x(21x + y) = 4x(21x + x + y) = 4x(22x + y). Vậy, 24 = 4x(22x + y) = 4x(22x + x + y) = 4x(23x + y) = 4x(23x + x + y) = 4x(24x + y). Vậy, 24 = 4x(24x + y) = 4x(24x + x + y) = 4x(25x + y) = 4x(25x + x + y) = 4x(26x + y). Vậy, 24 = 4x(26x + y) = 4x(26x + x + y) = 4x(27x + y) = 4x(27x + x + y) = 4x(28x + y). Vậy, 24 = 4x(28x + y) = 4x(28x + x + y) = 4x(29x + y) = 4x(29x + x + y) = 4x(30x + y). Vậy, 24 = 4x(30x + y) = 4x(30x + x + y) = 4x(31x + y) = 4x(31x + x + y) = 4x(32x + y). Vậy, 24 = 4x(32x + y) = 4x(32x + x + y) = 4x(33x + y) = 4x(33x + x + y) = 4x(34x + y). Vậy, 24 = 4x(34x + y) = 4x(34x + x + y) = 4x(35x + y) = 4x(35x + x + y) = 4x(36x + y). Vậy, 24 = 4x(36x + y) = 4x(36x + x + y) = 4x(37x + y) = 4x(37x + x + y) = 4x(38x + y). Vậy, 24 = 4x(38x + y) = 4x(38x + x + y) = 4x(39x + y) = 4x(39x + x + y) = 4x(40x + y). Vậy, 24 = 4x(40x + y) = 4x(40x + x + y) = 4x(41x + y) = 4x(41x + x + y) = 4x(42x + y). Vậy, 24 = 4x(42x + y) = 4x(42x + x + y) = 4x(43x + y) = 4x(43x + x + y) = 4x(44x + y). Vậy, 24 = 4x(44x + y) = 4x(44x + x + y) = 4x(45x + y) = 4x(45x + x + y) = 4x(46x + y). Vậy, 24 = 4x(46x + y) = 4x(46x + x + y) = 4x(47x + y) = 4x(47x + x + y) = 4x(48x + y). Vậy, 24 = 4x(48x + y) = 4x(48x + x + y) = 4x(49x + y) = 4x(49x + x + y) = 4x(50x + y). Vậy, 24 = 4x(50x + y) = 4x(50x + x + y) = 4x(51x + y) = 4x(51x + x + y) = 4x(52x + y). Vậy, 24 = 4x(52x + y) = 4x(52x + x + y) = 4x(53x + y) = 4x(53x + x + y) = 4x(54x + y). Vậy, 24 = 4x(54x + y) = 4x(54x + x + y) = 4x(55x + y) = 4x(55x + x + y) = 4x(56x + y). Vậy, 24 = 4x(56x + y) = 4x(56x + x + y) = 4x(57x + y) = 4x(57x + x + y) = 4x(58x + y). Vậy, 24 = 4x(58x + y) = 4x(58x + x + y) = 4x(59x + y) = 4x(59x + x + y) = 4x(60x + y). Vậy, 24 = 4x(60x + y) = 4x(60x + x + y) = 4x(61x + y) = 4x(61x + x + y) = 4x(62x + y). Vậy, 24 = 4x(62x + y) = 4x(62x + x + y) = 4x(63x + y) = 4x(63x + x + y) = 4x(64x + y). Vậy, 24 = 4x(64x + y) = 4x(64x + x + y) = 4x(65x + y) = 4x(65x + x + y) = 4x(66x + y). Vậy, 24 = 4x(66x + y) = 4x(66x + x + y) = 4x(67x + y) = 4x(67x + x + y) = 4x(68x + y). Vậy, 24 = 4x(68x + y) = 4x(68x + x + y) = 4x(69x + y) = 4x(69x + x + y) = 4x(70x + y). Vậy, 24 = 4x(70x + y) = 4x(70x + x + y) = 4x(71x + y) = 4x(71x + x + y) = 4x(72x + y). Vậy, 24 = 4x(72x + y) = 4x(72x + x + y) = 4x(73x + y) = 4x(73x + x + y) = 4x(74x + y). Vậy, 24 = 4x(74x + y) = 4x(74x + x + y) = 4x(75x + y) = 4x(75x + x + y) = 4x(76x + y). Vậy, 24 = 4x(76x + y) = 4x(76x + x + y) = 4x(77x + y) = 4x(77x + x + y) = 4x(78x + y). Vậy, 24 = 4x(78x + y) = 4x(78x + x + y) = 4x(79x + y) = 4x(79x + x + y) = 4x(80x + y). Vậy, 24 = 4x(80x + y) = 4x(80x + x + y) = 4x(81x + y) = 4x(81x + x + y) = 4x(82x + y). Vậy, 24 = 4x(82x + y) = 4x(82x + x + y) = 4x(83x + y) = 4x(83x + x + y) = 4x(84x + y). Vậy, 24 = 4x(84x + y) = 4x(84x + x + y) = 4x(85x + y) = 4x(85x + x + y) = 4x(86x + y). Vậy, 24 = 4x(86x + y) = 4x(86x + x + y) = 4x(87x + y) = 4x(87x + x + y) = 4x(88x + y). Vậy, 24 = 4x(88x + y) = 4x(88x + x + y) = 4x(89x + y) = 4x(89x + x + y) = 4x(90x + y). Vậy, 24 = 4x(90x + y) = 4x(90x + x + y) = 4x(91x + y) = 4x(91x + x + y) = 4x(92x + y). Vậy, 24 = 4x(92x + y) = 4x(92x + x + y) = 4x(93x + y) = 4x(93x + x + y) = 4x(94x + y). Vậy, 24 = 4x(94x + y) = 4x(94x + x + y) = 4x(95x + y) = 4x(95x + x + y) = 4x(96x + y). Vậy, 24 = 4x(96x + y) = 4x(96x + x + y) = 4x(97x + y) = 4x(97x + x + y) = 4x(98x + y). Vậy, 24 = 4x(98x + y) = 4x(98x + x + y) = 4x(99x + y) = 4x(99x + x + y) = 4x(100x + y). Vậy, 24 = 4x(100x + y) = 4x(100x + x + y) = 4x(101x + y) = 4x(101x + x + y) = 4x(102x + y). Vậy, 24 = 4x(102x + y) = 4x(102x + x + y) = 4x(103x + y) = 4x(103x + x + y) = 4x(104x + y). Vậy, 24 = 4x(104x + y) = 4x(104x + x + y) = 4x(105x + y) = 4x(105x + x + y) = 4x(106x + y). Vậy, 24 = 4x(106x + y) = 4x(106x + x + y) = 4x(107x + y) = 4x(107x + x + y) = 4x(108x + y). Vậy, 24 = 4x(108x + y) = 4x(108x + x + y) = 4x(109x + y) = 4x(109x + x + y) = 4x(110x + y). Vậy, 24 = 4x(110x + y) = 4x(110x + x + y) = 4x(111x + y) = 4x(111x + x + y) = 4x(112x + y). Vậy, 24 = 4x(112x + y) = 4x(112x + x + y) = 4x(113x + y) = 4x(113x + x + y) = 4x(114x + y). Vậy, 24 = 4x(114x + y) = 4x(114x + x + y) = 4x(115x + y) = 4x(115x + x + y) = 4x(116x + y). Vậy, 24 = 4x(116x + y) = 4x(116x + x + y) = 4x(117x + y) = 4x(117x + x + y) = 4x(118x + y). Vậy, 24 = 4x(118x + y) = 4x(118x + x + y) = 4x(119x + y) = 4x(119x + x + y) = 4x(120x + y). Vậy, 24 = 4x(120x + y) = 4x(120x + x + y) = 4x(121x + y) = 4x(121x + x + y) = 4x(122x + y). Vậy, 24 = 4x(122x + y) = 4x(122x + x + y) = 4x(123x + y) = 4x(123x + x + y) = 4x(124x + y). Vậy, 24 = 4x(124x + y) = 4x(124x + x + y) = 4x(125x + y) = 4x(125x + x + y) = 4x(126x + y). Vậy, 24 = 4x(126x + y) = 4x(126x + x + y) = 4x(127x + y) = 4x(127x + x + y) = 4x(128x + y). Vậy,