play with trigo

Geometry Level 2

Sinx + 2 cosx=1

0 <x <90

find 2sinx - cosx= ?

2 1/2 -1 1

1 solution

Harshit Joshi
Sep 8, 2014

sinx+2cosx=1

2sinx-cosx=a

square both of them and add them

u get, 5(sin^2 x + cos^2 x) +1 -1 = 1+a^2

5=1+a^2

a=+-2

hence a=2

In the fourth line of your solution, where you have "1 - 1", I think you meant " $4\sin(x)\cos(x) - 4\sin(x)\cos(x)$ " instead. :)

@Sonam Narang There is no solution to $\sin(x) + 2\cos(x) = 1$ on the interval $0 \lt x \lt 90$ ; the closest is $90$ degrees itself. So I think it would be more accurate if the given interval was $0 \le x \le 90$ .

Brian Charlesworth - 6 years, 9 months ago

play with trigo

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