|
|
|
|
đặt câu hỏi
|
T5
|
|
|
|
Without using trigonometry formula, prove the following equalities
1, $\cos 36.\cos 72=\frac{1}{4}$
2, $\tan 36.\tan72=\sqrt{5}$
|
|
|
|
bình luận
|
Bài 2
Sorry, I had to repair
|
|
|
|
|
|
|
|
sửa đổi
|
Bài 2
|
|
|
|
Bài 2 Let ABC be a triangle and let M be the midpoint of BC such that AB=5cm, AM=6cm and AC=13cm. The line through B and perpendicular to BC meets AB at E. Prove that CD is perpendicular to ME
Bài 2 Let ABC be a triangle and let M be the midpoint of BC such that AB=5cm, AM=6cm and AC=13cm. The line through B and perpendicular to BC meets AB at D, the line through C and perpendicular to BC meets AB at E. Prove that CD is perpendicular to ME
|
|
|
|
đặt câu hỏi
|
T4
|
|
|
|
Let O be the midpoint of a line sement Ab=2a, In the half-plane with edge AB, draw two rays Ax, By both perpendicular to AB. Choose M and N on Ax and By respectively such that MN=AM +BN. let H be the foot of the altitude from O onto MN. Find the possitions of M and N such that the area of the triangle HAB greatest possible
|
|
|
|
|
|
sửa đổi
|
Bài 2
|
|
|
|
Bài 2 Let ABC be a triangle and let M be the midpoint of BC such that AB=5cm, AM=6cm and AC=13cm. The line through B and perpendicular to BC meets AB at E. Prove that CD is perpendicular to ME
Bài 2 Let ABC be a triangle and let M be the midpoint of BC such that AB=5cm, AM=6cm and AC=13cm. The line through B and perpendicular to BC meets AB at E. Prove that CD is perpendicular to ME
|
|
|
|
đặt câu hỏi
|
T3
|
|
|
|
Find all pair of real numbers and be so that $a+b=\frac{\sqrt[4]{8}}{2}$ and $A=a^4-6a^2b^2+b^4$ is a positive integer
|
|
|
|
đặt câu hỏi
|
Bài 2
|
|
|
|
Let ABC be a triangle and let M be the midpoint of BC such that AB=5cm, AM=6cm and AC=13cm. The line through B and perpendicular to BC meets AB at D, the line through C and perpendicular to BC meets AB at E. Prove that CD is perpendicular to ME
|
|
|
|
đặt câu hỏi
|
Bài 1
|
|
|
|
Does there exist a positive k such that $2^k+3^k$ is a perfect square
|
|
|
|
|
|
bình luận
|
Bài 105627
câu 1, mjh chưa học, chưa pjk, nhưng câu 2 thỳ hjh như bạn sai rồi, phải dùng chỉnh hợp chứ
|
|
|
|
|
|
|
|
|
|
|
|
bình luận
|
Bất phương trình.
Mak, Trần Hoàng Sơn, thực chất thỳ TH này kũng đâu cần phải xét 2 TH, ta chỉ xét ra 2 TH khi tìm bpt kóa 2 nghiệm pohaan biệt thui chứ
|
|
|
|
|
|