# Help with trigonometric equations

#### pksin

If sinA =1/2 and cosB =1/2, then the value of A + B = ?(Degree)

#### MarkFL

If we restrict the angles to the first quadrant, we may use the co-function identity to state:

$$\displaystyle \sin(A)=\cos(B)=\sin\left(90^{ \circ}-B\right)$$

Hence:

$$\displaystyle A=90^{\circ}-B$$

$$\displaystyle A+B=90^{\circ}$$

#### skipjack

Forum Staff
Without that restriction, the sum (modulo 360°) is 90°, 210° or 330°.

greg1313

#### idontknow

$$\displaystyle \arcsin(x)+\arccos(x)=\pi /2$$.

#### Jitender Kumar Chaurasia

Sin (A+B) = 1 by expansions and putting the values ...
A+B = 90