If tanA=3/7 find the values of 2cosAsinA-cosA/1+sin^2A-sinA-cos^2A?

If tanA = 3/7 find the value of 2cosAsinA-cosA//1+sin^2A-sinA-cos^2A?

1 Answer
Mar 8, 2018

Plug into calculator:

2(7/sqrt(3^2 + 7^2)(3/sqrt(3^2 + 7^2))-(7/sqrt(3^2 + 7^2)/1 + (3/sqrt(3^2 + 7^2))^2 - (3/sqrt(3^2 + 7^2)) - (7/sqrt(3^2 + 7^2))^2

Explanation:

If tan A = 3/7 then the hypotenuse of the triangle is =
sqrt(3^2 + 7^2)

Therefore since cos = a/h and sin = o/h then cos A = 7/sqrt(3^2 + 7^2) and sinA = 3/sqrt(3^2 + 7^2)

From this knowledge you should then be able to work out the rest on your calculator using:

2(7/sqrt(3^2 + 7^2)(3/sqrt(3^2 + 7^2))-(7/sqrt(3^2 + 7^2)/1 + (3/sqrt(3^2 + 7^2))^2 - (3/sqrt(3^2 + 7^2)) - (7/sqrt(3^2 + 7^2))^2