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How to calculate sin, cos and tan

SOH CAH TOA (imagining each as a triangle) S = sin C = cos T = tan O = opposite H = hypotenuse A = adjacent
PH
Answered by Phoebe H. • Maths tutor
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Use the product rule to differentiate y=2xsinx

The product rule states that y=uv and dy/dx=(u)dv/dx + (v)du/dx. As the equation is in this form we can let u=2x and v=sinx. Therefore du/dx=2 and dv/dx=cosx. Substituting for u and v we get dy/dx=(2x)(cosx)...
GK
Answered by Georgianna K. • Maths tutor
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Solve the simultaneous equations: 5x + 3y = 41 and 2x + 3y = 20 Do not use trial and error.

5x + 3y = 41 2) 2x + 3y = 20 Subtract equation 2) from equation 1) to cancel the y's (3y-3y = 0) . Next we subtract the x's (5x - 2x = 3x) and then finally we have 41 - 20 = 21. We now have that 3x = 21 ( re...
DT
Answered by David T. • Maths tutor
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Solve the equation "x^2 + 3x - 4 = 0".

Recognise that quadratic can be factorised: (x+4)(x-1)=0 This gives the solutions x=-4 and x=1 by inspection.
ZK
Answered by Zak K. • Maths tutor
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3x² = 75 Find the value of x.

First Simplify the numbers we know. Therefore we get: x 2 =75/3 which is the same as x 2 =25 Now find the square root of 25, which is 5 or -5. Therefore x=5 or -5
DB
Answered by Daniel B. • Maths tutor
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