Post a New Question

Maths

posted by .

Hi, can someone give me the answer to this question:
secA-tanA=1/4. Find cosA

I got: CosA=4(1-sinA) Is my answer good?




Now multply each side by (1+sinA)
CosA(1+sinA)=4 cos^2 A
CosA=1/4 (1+sinA)

16(1-sinA)=1+sinA
15=17SinA
So you have sinA, now find Cos A from your equation you originally solved.

  • Maths -

    Cos A= 4(1-(15/17))

    cos A= 4(12/17)

    Cos A= 48/17

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Trig

    Please help with this one. I've worked it out in so many ways and can't tell what's correct. sinA sinA ----- - ------ 1+sinA 1-sinA Which answer is correct for the problem above?
  2. maths(trigonometry)

    prove that sinA-cosA+1/sinA+cosA-1=1/secA-tanA
  3. trig

    Please help me how to do this: 1) 1 + sina*cosa / (cosa + sina)^2 = 2) sina + cosa / 1- 2sin^2a =
  4. trig

    I need to count this: a) 1-tg^2a/1+ctg^2a, when sina =2/3 b) 1-tg^2a/1-ctg^2a, when cosa= -1/3 c) tga * cos^2a, when sina + cosa=5/7 d) tg^2a + 1/sina * 1/cosa + ctg^2a, when tga + ctga =5
  5. further mathematics

    Let P=(cosA sinA) (sinA cosA) Q=(cosB sinA) (sinB cosA) show that PQ=(cosA(A-B) sin(A B)) (sinA(A B) cos(A-B))
  6. trig

    Establish the following identity: CosA/1-TanA + SinA/1-CotA = CosA-SinA
  7. Maths, Divine International Public School

    If 15Cot=8, find (1+SinA)(1-SinA)/(1+CosA)(1-CosA)
  8. trigonometry

    x×sin^3A=y , cos^3A = sinA × cosA , x×sinA= y×cosA , then prove that x^2+ y^2= 1 I have no idea
  9. Maths

    Prove that [sinA/(1-cosA)-(1-cosA)/sinA]*[cosA/(1+sinA)+(1+sinA)/cosA]=4cosecA I the second part as 2 secA
  10. maths trignometry

    Prove that. √seca+2sina/seca-2sina=Sina+cosa/sina-cosa

More Similar Questions

Post a New Question