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Maths
A Level

solve 2cos^2(x) - cos(x) = 0 on the interval 0<=x < 180

we start  y factoring and solving for each equation:

cos(x) (2cos(x) - 1) = 0 

this means: 

cos(x) = 0 and cos(x) = 1/2

from the first equation we get:   x = 90

and from...

DS
Answered by Dimitris S. Maths tutor
8669 Views

Express 2cos(x) + 5sin(x) in the form Rsin(x + a) where 0<a<90

Expanding Rsin(x + a): Rsin(x + a) = Rsin(x)cos(a) + Rcos(x)sin(a) Comparing coefficients of sin(x), cos(x) with first expression leads to: Rsin(a) = 2, Rcos(a) = 5 Dividing these equations gives: tan(a) ...

DH
Answered by Dan H. Maths tutor
11277 Views

A girl kicks a ball at a horizontal speed of 15ms^1 off of a ledge 20m above the ground. What is the horizontal displacement of the ball when it hits the ground?

As we are looking for the horizontal displacement first we look at horizontal motion. We know that the horizontal velocity is 15ms^-1 but we dont know the time so we can't work out the horizontal displace...

VW
Answered by Victoria W. Maths tutor
4019 Views

Differentiate tan^2(x) with respect to x

d/dx(tan^2(x)) is not a known differential, and therefore requires a substitution to calculate it using simpler known differentials.

Using the identity sin^2(x) + cos^2(x) = 1, the equation can be ...

HA
Answered by Harry A. Maths tutor
15547 Views

By first proving that sin2θ=2sinθcosθ, calculate ∫1+sinθcosθ dθ.

We have, from the formula book, sin⁡(A±B)=sinAcosB±cosAsinB Using A=B=θ, we have sinθ+θ=sinθcosθ+cosθsinθ Which we can simplify to sin2θ=2sinθcosθ as required. We can t...

AH
Answered by Abigail H. Maths tutor
7012 Views

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