![18. If three positive numbers a, b, c are in A.P. and frac{1}{a^{2}}, frac{1}{b^{2}}, frac{1}{c^{2}} also in A.P., then begin{array}{ll}{text { (1) } a=b=c} & {text { (c) }} {text { (2) } 18. If three positive numbers a, b, c are in A.P. and frac{1}{a^{2}}, frac{1}{b^{2}}, frac{1}{c^{2}} also in A.P., then begin{array}{ll}{text { (1) } a=b=c} & {text { (c) }} {text { (2) }](https://toppr-doubts-media.s3.amazonaws.com/images/10038822/8fdc646c-77db-495c-a333-c3b5d57e3711.jpg)
18. If three positive numbers a, b, c are in A.P. and frac{1}{a^{2}}, frac{1}{b^{2}}, frac{1}{c^{2}} also in A.P., then begin{array}{ll}{text { (1) } a=b=c} & {text { (c) }} {text { (2) }
![In triangle ABC, Angle ACB=90°, seg CD is perpendicular to seg AB, seg DE is perpendicular to seg CD. Show that: CD² x AC = AD x AB x DE. In triangle ABC, Angle ACB=90°, seg CD is perpendicular to seg AB, seg DE is perpendicular to seg CD. Show that: CD² x AC = AD x AB x DE.](https://1.bp.blogspot.com/-FN64TgPUmCg/W7Gxuq8_vNI/AAAAAAAAAqo/PS-P67drV3UeRA2Lw3BGMxngaC2RYN8ywCK4BGAYYCw/s1600/Similarity_Page_06.jpg)
In triangle ABC, Angle ACB=90°, seg CD is perpendicular to seg AB, seg DE is perpendicular to seg CD. Show that: CD² x AC = AD x AB x DE.
If the roots of the equation (a²+b²)x² 2b(a+c)x + (b²+c²) = 0 are equal, then A. 2b = a+c B. b² = ac C. b = 2ac/ a+c D. b = ac
![If the Roots of the Equation (C2 – Ab) X2 – 2 (A2 – Bc) X + B2 – Ac = 0 in X Are Equal, Then Show that Either a = 0 Or A3 + B3 + C3 = 3abc - Mathematics | Shaalaa.com If the Roots of the Equation (C2 – Ab) X2 – 2 (A2 – Bc) X + B2 – Ac = 0 in X Are Equal, Then Show that Either a = 0 Or A3 + B3 + C3 = 3abc - Mathematics | Shaalaa.com](https://www.shaalaa.com/images/_4:13616ae7a3054d3c9210a8dc730f7271.png)