Recent content by MrGoATi

  1. MrGoATi

    Trigonometry: count sin+cos when tg-ctg=-7/12

    yeah it kinda worked, I came real close but one additional - is there and i can't find a mistake.. so with first equation i make it sinycosy=(1+cos2x)/2 with the second. cos2x=2(sin(π/4)cosy-sinycos(π/4))2 both sin(π/4) and sin(π/4)=root2/2 and when squared = ½ cos2x=2(½sin2+½cos2-sincos)...
  2. MrGoATi

    Trigonometry: count sin+cos when tg-ctg=-7/12

    it's cos2x= -sin2(y) right? It does not help much though.
  3. MrGoATi

    Trigonometry: count sin+cos when tg-ctg=-7/12

    Forgot to say the radiant is between [0;90] oh, yeah. x2 + 7x/12 - 1 = 0 got x1=4/3 x2= - 3/4 my guess since it's tg and [0;90] is positive. tg = 4/3 and not -3/4 right? i know i can do sin = tgcos; so tgcos+cos =>(7/3)cos used tg2 = 1/cos2 cos = 3/5 and got the correct answer (7/3)*(3/5) =...
  4. MrGoATi

    Trigonometry: count sin+cos when tg-ctg=-7/12

    Mentor note: Moved thread to homework section ok So I'm doing supposedly easy trigonometry problems. i did the easiest ones. now I have no idea how to solve 2. first one is count sin+cos When tg - (1/tg) = -(7/12) what i figured is that i probably need to use...
  5. MrGoATi

    Ball dropped down from 5m, what is its speed when it hits the ground

    ok I guess it's just too complicated for me to understand, the change of up and down makes sense, but pytagoras WT*
  6. MrGoATi

    Ball dropped down from 5m, what is its speed when it hits the ground

    but g is usually used as a vector and it turns out negative most of the time does it not? did not think of this that way until now :wideeyed: in ##F= mg## ##E=mgh## ##s=at^2/2## it's not a vector so always positive? and in ##g=v-u/t## it depends on vector direction? you just made physics more...
  7. MrGoATi

    Ball dropped down from 5m, what is its speed when it hits the ground

    how could getting right answer by altering values,formulas and known data be helpful? like yeah I can easily get correct answer by changing it to your suggested ideas but when I'm at exam and I do not think of that when trying to do exercise I will still get wrong answer or if I use your idea in...
  8. MrGoATi

    Ball dropped down from 5m, what is its speed when it hits the ground

    sign of h is negative since down is always negative, and the travel was from higher altitude. g is usually negative but in this case it's somehow positive I got this question answered in another post, tho I'm not sure how I got multiple posts of this even though I made 1 XD.
  9. MrGoATi

    Ball dropped down from 5m, what is its speed when it hits the ground

    i guess it's as if the person is on a cliff and the cliff suddenly disappears and he is hit at the top of his head which gives him extra 5m/s velocity. i got an answer on another post though, in ##E_p=mgh## ##g=10m/s^2## instead of ##g=-10m/s^2##
  10. MrGoATi

    Ball dropped down from 5m, what is its speed when it hits the ground

    Homework Statement sportsman jumps at 5m/s velocity from 5m cliff to water. at what speed does he reach water? so given answer is 11.1m/s though in this book there are some wrong answers (I did try other equations and I got right answer but I want to know why I can't get it using this one)...
  11. MrGoATi

    Ball dropped in air at 20m/s, why v=20 not v0=20

    [ post: 5642023, member: 345636"]What you stated was not the exact statement of the problem as it was originally written. It was your paraphrasing of the problem statement. ,,ball dropped in air at 20m/s.,, that's the given information the question was ,maximum height, which i told when you...
  12. MrGoATi

    Ball dropped in air at 20m/s, why v=20 not v0=20

    i did completely state all that was given, and when you asked i answered what i needed to find. thanks for suggestion though i will keep that in mind
  13. MrGoATi

    Ball dropped in air at 20m/s, why v=20 not v0=20

    thanks, now i get it. explains a lot
  14. MrGoATi

    Ball dropped in air at 20m/s, why v=20 not v0=20

    yeah exactly but from a ton of forums I watched solutions to this they use s=v0xt+ gt2/2 but end up with s=gt2/2 finding that a ball thrown up with 20m/s will get to ground to maximum height in 2.04s, 20.4m the task is quite easy, but since it is so confusing for me that v0=0 I think I will be...
  15. MrGoATi

    Ball dropped in air at 20m/s, why v=20 not v0=20

    the task is to find maximum height, but I'm pretty sure it's 20.4 I am asking about whether velocity is v0 or v . and how do I know which is it in tasks I may have in future.
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