5sinA +3cosA = 4 find 3sinA + 5cosA Share with your friends Share 1 Manbar Singh answered this We have, 5 sin A + 3 cos A = 4⇒5 sin A + 3 cos A2 = 42⇒25 sin 2A + 9 cos2A + 30 sin A . cos A = 16⇒251-cos2A + 91-sin2A + 30 sin A . cos A = 16⇒25 - 25 cos2A + 9 - 9 sin2A + 30 sin A . cos A = 16⇒34 - 25 cos 2A - 9 sin2A + 30 sin A . cos A = 16⇒- 25 cos 2A - 9 sin2A + 30 sin A . cos A = 16 - 34⇒- 25 cos 2A - 9 sin2A + 30 sin A . cos A = -18⇒ 25 cos 2A + 9 sin2A - 30 sin A . cos A = 18⇒5 cos A - 3 sin A2 = 18⇒5 cos A - 3 sin A = ±32 2 View Full Answer Siddhartha Chaudhary answered this FIRST SQUARE 5SINa + COSa =4 then change SIN^2a and COS^2a into 1 - COS^2a and 1 - SIN^2a you will get the desired result the answer is 18 0
