Prove the trigonometric identity tan^2(x)+1=sec^2(x)

 We can start with the identity sin2(x)+cos2(x)=1 If we divide through the equation by cos2(x), we get: sin2(x)/cos2(x) + cos2(x)/cos2(x) = 1/cos2(x) If we look at the left hand side of the equation: sin2(x)/cos2(x) is equal to tan2(x), and cos2(x)/cos2(x) is equal to 1 (as it is divided through by itself), the left hand side becomes tan2(x) +1 Now if we look at the right hand side of the equation: 1/cos2(x) is equal to sec2(x) Putting both sides of the equation together, we get tan2(x) +1=sec2(x)

CW

Related Maths A Level answers

All answers ▸

The radius of a circular disc is increasing at a constant rate of 0.003cm/s. Find the rate at which the area is increasing when the radius is 20cm.


use the substitution u=2+ln(x) to show that int(e,1(ln(x)/x(2+ln(x)^2))dx)=p+ln(q) , where p and q are rational numbers.


When you integrate a function why do you add a constant?


Work out the equation of the normal to the curve y = x^3 + 2x^2 - 5 at the point where x = -2. [5 marks]