Cho hình chóp S.ABC có SA, SB, SC đối một vuông góc và SB+SC = SA = 3a . Gọi S (I; R) là mặt cầu tâm I, bán kính R tiếp xúc với tất cả các mặt của hình chóp S.ABC và nằm ngoài hình chóp S.ABC đồng thời I và S nằm về 2 phía đổi với mặt phăng (ABC) (nói cách khác S. (I; R) là mặt cầu bàng tiếp mặt đáy (ABC) của hình chóp S.ABC ). Tính bán kính R theo a. A. 5a/4. B. a. C. За/4 D. 3a/2 Giải em chi tiết câu này với ạ.. Em cảm ơn ạ

Cho a,b,c lớn hơn 0 và a+bc = 1/a + 1/b + 1/c Chứng minh: Căn a^2/ 1+3bc + Căn b^2/ 1+ 3ac + Căn c^2/ 1+ 3ba lớn hơn hoặc bằng 3/2 Giúp mk bài toán này với ạ

Nhờ các bạn giúp mình làm bài tập này ạ 78.4:(15.7-7.86)*4.12

Finish the second sentences so that it has the same meaning as the first one. 1, Because she has an injured leg, she cannot participate in the event. -> Due to ________________ 2, They couldn't make a sensible decision beacause they were under pressure. -> Due to ________________ 3, Because my father didn't hear me, he didn't make a single response. ->Because of _______________________ 4, They equip their house with noise resistant windows because they have to deal with noise pollution. ->Because of _______________________ 5, They were help up in the traffic for a long time, so they were a little impatient. -> Due to ________________ 6, Because they are not old enough, they cannot drive a car. ->Because of _______________________

Đc kon các bạn ơi với giúp mình viết kết bài với ạ

1,25*99-1,25+1,25*2.hãy tính một cách thuận tiện nhất

1)to reduce traffic and pollution, motorist are encouraged to switch to ... transport.A private B public C common D cheap 2)More people will……a bus instead of using their car if it is comfortable and cheap.A ride B drive C buy D take 3)It’s against safety regulations to…. A motorbike without wearing a helmet,A go by B travel C drive D ride 4)Susan…..wear glasses but now she wears contact lenes.A used to B didn’t use to C use to D never use to 5) What did you…..have for lunch when you were at primary school?A used to B use to C did use to D didin’t use to. 6)My friend (used to take/use to take/took/never used to take) an English-speaking course last year. 7)Paul(didn’t use/didn’t use to/would/not used to)like Hallowen when he was young

Finish the second sentences so that it has the same meaning as the first one. 1, Because there is a lot of smoke, the air is polluted. ->Because of _______________________ 2, Because there was an accident, the traffic was block. ->Because of _______________________ 3, She cannot go out tonight because she has a great deal of homework. ->Because of _______________________ 4, Because there have been changes in the temperature of water, the living pattern of the marine animals have changed. -> Due to ________________ 5, They are in a difficult situation, so they have to consult their professor. -> Due to ________________ 6, The flight will be put off until 8a.m because there is thick fog. -> Due to ________________

1,25*99+1,25-1,25*2.hãy tính một cách thuận tiện nhất

Viêt đoạn văn (12 đên 15 câu ) bàn về 1 tac phẩm mà em yêu thich nhât co tac động và y nghĩa đên vơi mọi người